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SCIENCE LIB. 
S 

. H3 



'^i 



I 



THE 



ROTHAMSTED MEMOIRS 



OK 



AGBICULTUKAL CHEMISTKY 



ASJ> 



PHYSIOLOGY. 



' BY 

8iB JOHN BEKNBT LAWES, Babt., D.C.L., LL.D., F.K.S., F.C.S., &a, 

OP B0THAM8TED, H15BT8., 
AND 

Sn JOSEPH HENBY GILBEBT, M.A., Ph.D., LL.D., F.B.S., V.P.C.S., &o. 



Volume I. 

CONTAINING REPORTS OF 

FIELD EXPERIMENTS, 

EXPERIMENTS ON VEGETATION, 

dc, dtc. 

Published 1847 — 1863 inolusive. 



LONDON: 
PRINTED BY WILLLA.M CLOWES AND SONS, LIMITED, 

8TAMF0BD 8TRBBT AND OUABINQ 0R088. 

1893. 



ROTHAMSTED MEMOIRS. 



CONTENTS OF VOL. I. 



REPORTS OF FIELD EXPERIMENTS, &c., &c. 



Published 

1. Agricnltnral Chemistry (Jour. Roy. Ag. Soc. Eng., vol. viii., p. 226.) 1847 

2. Agricultural Chemistry, Turnip Culture (Jour. Roy. Ag. Soc. Eng., 

vol. viii., p. 494.) .. .. .. .. .. .. .. 1847 

3. Experimental Investigation into the amount of Water given off by 

Plants during their Growth, especiaUy in relation to the fixation 
and source of their various Constituents (Jour. Hort. Soo. Lond., 

vol. v., p. oo») .. .. •. .. .. •• .. .• loOU 

4. Report of some Experiments undertaken at the suggestion of Professor 

Xiindley, to ascertain the comparative Evaporating Properties of 
Evergreen and Deciduous Trees (Jour. Hort. Soc. Lond., vol. vi.. 

Pa itmt .y.. .. .. •• .• .• .. •. ..1 oO 1. 

5. Agricultural Chemistry, especially in relation to the Mineral Theory 

of Baron Liebig (Jour. Roy. Ag. Soc. Eng., vol. xii., p. 1.) 1851 

0. On the Amounts of, and Methods of estimating. Ammonia and 
Nitric Acid in Rain-water (Report of the British Association for 
the Advancement of Science for 1854) .. .. .. 1854 

7. Report to the Right Hon. the Earl of Leicester on the Experiments, 

conducted by Mr. Keary, on the Growth of Wheat upon the same 
land for four successive years, at Holkham Park Farm (Jour. 
Roy. Ag. Soc. Eng., vol. xvi., p. 207.) 1855 

8. On some points connected with Agricultural Chemistry; being a 

reply to Baron Liebig's " Principles of Agricultural Chemistry " 
(Jour. Roy. Ag. Soc Eng., vol. xvi., p. 411.) .. .. .. 1855 

9. On the Growth of Wheat by the Lois Weedon System, on the 

Rothamsted Soil ; and on the Combined Nitrogen in Soils (Jour. 
Roy. Ag. Soc. Eng., vol. xvii., p. 582.) .. .. 185G 

10. On some points in the Composition of Wheat Grain, its Products in 
the Mill, and Bread (Journal of the Chemical Society of London, 
vol. X. p< 1.) •« ... •• lo57 



338561 



IV CONTENTS OF VOL. I. 

Published 

11. On the Growth of Barley by differeDt Manures oontinuously on the 

same Land ; and on the Position of the Crop in Rotation (Jonr. 
Roy. Ag. Soc. £ng., vol. xviii., p. 454.) .. .. 1857 

12. Report of Experiments with different Manures on Permanent Meadow 

Land, with Tabular Appendix (Jour. Roy. Ag. Soc. Eng., vols. 

xix., p. 552, and XX., pp. 228 and 398.) 1858-9 

13. Report of Experiments on the Growth of Red Glover by different 

Manures (Jour. Roy. Ag. Soc. Eng., vol. xxi., p. 178.) 1860 

14. On the Sources of the Nitrogen of Vegetation ; with special reference 

to the question whether Pleoits assimilate free or uncombined 
Nitrogen — Abstract (Proceedings of the Royal Society of London, 
vol. X., p. 544.) . . . . . . . . . . . . 1860 

15. On the Application of different Manures to different Crops, and on 

their proper Distribution on the Farm 1861 

16. On some points in connection with the Exhaustion of Soils — ^Abstract 

(Report of the British Associatibn for the Advancement of Science 

for 1861) .. .. .. .. .. .. 1861 

17. Report of Experiments made at Rodmersham, Kent, on the Growth 

of Wheat by different descriptions of Manure, for several years in 
succession on the same Land (Jour. Roy. Ag. Soc. Eng., voL 

XXlll., p. «5x.^ .. .. .. .. '. • .. .. .. Ioua 

18. The Effect of different Manures on the Mixed Herbage of Grass-Land 

(Jour. Roy. Ag. Soc. Eng., voL xxiv., p. 131.) .. 1863 



r 



ON 



AGRICULTURAL CHEMISTRY 



BY 



JOHN BENNET LAWES, 



LONDON: 

PRINTED BY W. CLOWBS A SONS, STAMFORD STREET. 

1847. 



I 



BE-PRINTED BY DUNN & CHIDGEY, 165-57, KINGSLAND ROAD, B. 

1888. 



FROM THE 
JOUENAL OF THE ROYAL AGRICULTURAL SOOIETi', 

VOL. VIIL, PART I. 



AGRICULTURAL CHEMISTRY. 



It 18 a matter of surprise that so little is actually known upon the 
theory of agriculture. Its practice is nearly coeval with man- 
kini while as yet it scarcely exists as a science. Ask the most 
experienced farmer to explain the principles which govern the 
routine he is daily in the habit of practising ? Ask him to deter- 
mine the value of any rotation of crops, or their comparative ex- 
hausting powers ? Ask him what ingredients must be restored to 
the soil to keep its fertility unimpaired ? or the exact manner in 
which climate mfluences his produce ? His answers will be vague 
and unsatisfactory. But these, and a thousand other questions of 
a similar nature, are capable of solution by science, and they must 
be answered before agriculture can be said to rest upon a satis- 
factorv foimdation. 

Independently of the money which must annually be lost in fruit- 
less experiments, the disadvantages attending the want of fixed rules 
in agriculture are many. Numbers of men possessing capital are 
deterred from farming by the proverbial uncertainty of the profits 
attending it ; and many who follow the profession of agriculture, 
and have the means, will not freely embark their money on 
the improvement of their farms, for want of that knowledge 
which would enable them to calculate their returns with any de- 
cree of certainty. Hence, too, the tenant farmer is frequently 
compelled to adopt a rotation of crops entirely prejmJicial to his 
interest, retained only because it happened to be the custom of 
our ancestors a century ago, while the same rotation is enforced 
upon the farmer who expends 8/. an acre on his land, as upon 
him who expends only 3Z. 

Liebig's work on Agricultural Chemistry, published in the 
year 1840, attracted very generally the attention of British agri- 
culturists. In those pages they were first made acquainted with 
the important aid they were likely to obtain from the science of 
chemistry applied to the cultivation of the soil. The work of 
Sir Humphrey Davy upon the same subjeot can hardly be said to 
have influenced tne practice of agriculture. He applied the 
knowledge of chemistry, as it then existed, with his umial sagacity, 
but at the period in which he ^vrote organie chemistry was quite 
in its infancy. The labours of the German and French chemists 
during the last thirty years have principally been directed to the 
.study of organic chemistry^ which owes its present important 
position to the number of accurate analyses they have given to the 
world. It is much to be regretted that Liebig should have 
altered, in the third edition of his work, so many of the views and 

B 2 



4 On Agricultural GJienmtry. 

opinions laid down in the first ; or that a hasty visit to England, 
dnring which (a8 he says in his preface) he made himsett ac- 
quainted with practical agriculture, should have caused him to 
pronounce as valueless the experiments of Boussingault, whose 
opinions are entitled to respect, as coming from one in whom 
are comhined the scientific chemist and the practical farmer. 
Without entering into the merits of the different opinions main- 
tained by these distinguished chemists, I may here observe that 
many of the errors into which Liebig has fallen, have, I think, 
arisen from his not sufficiently considering what agriculture really 
is. Practical agriculture cmisists in the artificial accumulation of 
certain constituents to he employed either as food for man or other 
ayiimalsy wpon a space of ground imupahU of supporting them in its 
natural state. This definition of agriculture is, I think, import- 
ant, as distinguishing English agriculture at least from the system 
pursued in various parts of the world, where the population is 
small and the land of little value, viz., of taking only the natural 
produce of the soil, without any effort to increase it, and in time 
abandoning ifc for a soil as yet undisturbed. If Liebig had suffi- 
ciently considered this distinction, he would not have assumed 
that certain substances employed as manures are of little value, 
because plants and trees in their natural state, are capable of 
obtaining them in sufficient quantity for their use. The great 
problem to be solved with regard to manures is, what substances 
IS it necessary to supply to the soil in order to maintain a re- 
munerative fertihtjr ^ The solution of this question appears easy 
enough, regard bemg had only to the composition of the crops 
removed. PracticaUy there are, however, great difficulties attend- 
ing it, which can only be entirely overcome by a long series of 
careful and costly experiments. If the ash theory advanced by 
Liebig, and so industriously propagated by his pupils, were 
founded on truth, a careful examination of the ashes of plants, and 
a few simple calculations upon the amount of mineral substances 
exported from the soil in corn, meat, &c., would at once enable 
us to explain and remedy the exliaustion of our soils. The 
farmer, when he sends his load of wheat to market, would bring 
back the few pounds of minerals which the wheat contained, and 
the return of these to the soil would enable him to produce the 
same amount of wheat for the market the following year. Un- 
fortunately, however, the ground-work upon which this theory is 
raised is unsound, when agriculture, as aistinguished from natural 
vegetation, fonns the subject of consideration. 

Agricultural plants, which practice has shown to differ widely 
from each other in their respective relations to soil, climate 
manuring, and position in rotation, possess at the same time 
widely differing powers of reliance upon the atmosphere for the 



On Agricultural Chemistry, 5 

GonBtitaents which it is known to supply in a greater or less de- 
gree. If grain crops held the same relation to natural and arti- 
ficial supply of their organic constituents, as the leguminous plants 
and turnips, the farmer would not require the assistance of the 
latter crops ; but since, compared with these, the grain crops are 
in some important respects far more dependent upon artificial 
supply to the soil of ceit-ain organic constituents, of which the 
price is high and the supply limited, it becomes necessary to 
employ certain plants which possess the power of collecting these 
ingredients from the atmosphere, and such procedure constitutes 
a rotation of crops. 

For some years past I have been engaged in a very extensive series 
of experiments upon my farm, with a view to determine some of 
the more important questions which are constantly arising in the 
minds of agriculturists. It would be impossible in a paper of 
this description to enter into a detail of the plan I have pursued 
in conducting these experiments. Keeping in mind the motto of 
the Society, ^Practice irith scieyue,^ I shall now merely select 
those results which bear most upon practical agriculture, and 
which appear to me most suitable to my present purpose. The 
greater portion of these experiments, and the various points of 
science connected with them, will be discussed with more pro- 
priety in an independent work. The views which I have adopted, 
and which I shall now endeavour to explain, have arisen during 
the course of these experiments ; but it is very probable I shall 
have reason to modify them as the investigation proceeds. 

I certainly place great reliance on the experimental results 
which I possess ; every operation has been conducted under the 
eye of Dr. Gilbert, a gentleman who received his scientific edu- 
cation in the best British and continental laboratories, and has 
applied that accuracy which modern science demands, both to the 
operations of the laboratory and the field. 

In the first place I shall offer some general remarks upon the 
growth and nature of the common agricultural plants, and after- 
wards endeavour to show the effect of manures upon them. 

The crops which form a rotation belong, botanically speaking, 
for the most part to the three following natural orders of plants: — 
The Oramima^ containing wheat, barley, oats, rye, and the 
grasses which constitute our natural pastures; the Leguminos<By 
containing beans, peas, tares, lucerne, clover, trefoil, saintfoil, 
&c. ; and the GriwifercBy containing turnips and rape. The 
SolanecR^ yielding the potato, and the Umbelliferos, carrots and 
parsnips may also be noticed. For the purposes of agriculture, 
however, a different system of classification might be adopted with 
advantage, having reference to the organ or part of the plant which 
is the object of cultivation. In clover, tares, and pasture, we 
generally require leaf and stem, which may be termed the primary 



6 



On Agricultural Chemistry. 



organs of plants ; in the tumip we require the bulb or intermediate 
organ ; and in the grain crops, peas, beans, &c., the ultimate 
organ, the seed. 

In considering this subject it is necessary to bear in mind that 
the natural aim of every plant is to produce a perfect seed, and 
that, when growing in a soil and climate adapted to its special 
habits and peculiarities, it produces no more of each organ than it 
requires for the healthy perpetuation and reproduction of see<l. 
When the leaf has fulfilled its office, the nutritious fluids circu- 
lating through it are withdrawn, and it decays or dries up. 
These fluids enter into the stem, and, rising higher and higher, 
are at length deposited in the seed. Plants are therefore required 
by agriculturists in two distinct conditions, one in which the 
nourishment is more or less circulatory, the other in which it is 
fully elaborated and deposited : in one case water constitutes 
above threc-fourtlis of the weight of the produce ; in the other it 
does not generally amount to one-fifth. Although the agricul- 
turist ix)ssesses the means of developing the circulatory or elabo- 
ratory conditions of plants by manures and mechanical operations, 
climate exerts the greatest influence over them. By climate I 
mean the quantity of rain that falls, the number of days on which 
it falls, and the temperature during the period when the plant is 
actively growing or forming seed. 

As the experiments to which I am about to refer were per- 
formed during the seasons of 1844, 5, and 6, I wish to make a 
few observations upon the climate of each season, and to show 
how the general condition of the crop was influenced by it. The 
temperature and fall of rain I have taken from the tables 
published by the Horticultural Society at Chiswick, from which 
my farm is little more than 20 miles distant, consequently the 
climate may be said to be nearly identical. 

Table I. 



Number of day«' Rain during 30 wk«. and 4 days. 


Inches of Rain during 80 weeks and 4 dayn. 




1844 


1845 


1846 




1844 


1845 


1846 


April . 
May . 
June . 
July . 
August 
September 
October . 


7 
7 
10 
10 
16 
12 
19 


15 
21 
8 
21 
21 
11 
18 


18 
10 

2 
16 
17 

6 
24 


April 

May. 

June 

July . . 

August 

Septemb< 

October 


1 • 


0-88 
0-26 
0-97 
1-94 
2-00 
1-27 
419 


0-99 
2-88 
0-98 
216 
3-32 
1-68 
1-48 


3-84 
1-35 
0-64 
1-60 
4-82 
1-39 
5-50 




81 


110 


93 






10-96 


18-49 


1914 



Oa Agricultural Chemistry. 







Table I. — continued. 








M««ii Tempeiatare during 30 weeks and 4 days. 


Mean Temperatare above or below average. 




1844 


1845 


1846 


April 
May . 
June. 
Jnly . 
August . 


1844 


1845 


1846 


April . 

May . . . 

June . 

July . . . 

August 

September 


511 
54-2 
62-3 
64-3 

60-4 
60 
50-2 


48-3 
49-5 
61-8 
620 
58-9 
55-2 
51-2 


47-0 
o5*7 
66-3 
64-7 
65-2 
62-5 
52-7 


4 above 

i below 

2 above 

1*6 above 

2-2b€low 


I '0 above 
18 above 
0-9 below 
0-9 below 
4*6 below 


Average 

3 above 

6i above 

2 above 

27 above 


October . 








57o 


55-3 


591 









The season of 1844 was remarkable for bad crops of hay, clover, 
late-sowu barley, and oats, very fine wheat with very short straw, 
and average turnip crop. In 1845 there was abundance of hay 
and clover, bad quality of wheat, abundance of straw, and one of 
ohe largest crops of turnips ever known. In 1846 the grass and 
first crops of clover were unusually abundant, wheat was of very 
fine quality, straw moderate, turnips deficient. Of course, there 
are plenty of exceptions to what I have stated, and these remarks 
do not apply to those places in which the climate varies much from 
that of London ; but I have given what I believe to be the general 
character of the crops within a circle of 100 miles from London. 

The soil upon which my experiments were tried consists of 
rather a heavy loam resting upon chalk, capable of producing 
good wheat when well manured, not sufficiently heavy for beans, 
but too heavy for good turnips or barley. The avei*age produce 
of wheat in the neighbourhood is said to be less than ^12 bushels 
per acre, wheat being grow^n once in five years. The rent varies 
from 20s. to 26s. per acre, tithe free. The fields selected for 
purposes of experiment had been reduced to the lowest state of 
fertility by removing a certain number of corn crops without ap- 
plying any manure, and wheat and turnips were chosen for the 
subjects of investigation. The wheat-field consists of 14 acres, 
the crops removed since it was manured, barley, peas, wheat, oats. 
In 1844, the first experimental wheat crop was harvested, and the 
fourth is now growmg. The turnip-field had not long Ixjen 
taken in hand, and was known to be in so poor a condition that it 
was at once put under experiment, and in 1843 the first crop of 
turnips was sown, and they have been continued each year smce, 
the produce being removed and weighed. The wheat-field was 
divided into a certain number of equal spaces, of which one has 
Ijeen left unmanured, and ojie received 14 tons of dung every 
year ; the remainder of the plots received different descriptions 
and quantities of artificial manures. 



8 



On Agricultural Chemist?!/. 



Table 2. 



No. of Days' Rain dnring April and May (Grass ) 
Season) I 

No. of Days' Rain from May to end of August — 17 i 
weeks (Grain Season) j 

No. of Days' Rain from June to end of October — 21 / 
weeks (Turnip Season) j 

Inches of Rain dnrirg April and May (Grass Season) 
Inches of Rain from May to end of August — 17 weeks \ 

(Grain Season) I 

Inches of Rain from June to end of October — 21 weeks | 

(Turnip Season) I 

Mean Temperature during April and May (Grass ( 
Season) ) 

Mean Temperature from May to end of August — 17 | 
we«»k8 (Grain Season) ) 

Mean Temperature from June to end of October — 21 ) 
weeks (Turnip Season) l' 

Temperature above or below average from May to | 
end of August (Grain Season) .... / 



1844 



14 
43 
67 

0-59 
517 

10-37 

52-6 

60-3 

59-4 

above 
0-9 



1845 



36 
71 
74 

3-87 
9-34 

9-62 

48-9 

.58-2 

57-8 

below 
21 



1846 



28 
45 
6.> 

519 
8-41 

13-95 

50-5 

631 

62-2 

above 
3-2 



The above table gives the climate of the three years from the 
beginning of May till the end of October. I have considered 
the climate as affecting the grass to be that of April and May; 
wheat-climate to commence with May and end with August ; 
turnip season to begin with June and end with October : — 

It will be seen that the two spring months of 1844, April and 
May, were unusually dry ; the quantity of rain and the number 
of days in which it fell were both small ; the summer was hot 
and dry, and the autumn moderately rainy. An entire absence 
of the climate necessary for an enhanced accumulative and cir- 
culating condition of plants prevented the favourable growth of 
the spring crops, and a hot and dry summer favoured the depo- 
siting and elaborative condition, and produced good quality of 
grain. In 1845 the great nmnber of wet days and the low tem- 
perature of the summer were highly favourable to a circulatory 
condition of the plant, consequently green crops of every de- 
scription and straw were unusually abundant, and grain of bad 
quality. In 1846 the spring was very favourable to a circulating 
condition, producing luxuriant crops of grass and clover. The 
month of June, when the grain was forming seed, had a tempera- 
ture 6^^ above the average, with only two days in which rain fell, 
and produced very fine quality of grain. The inferior crops of 
turnip obtained that year, notwithstanding the large total amount 
of ram, arose from the almost entire absence of rain for thirty-one 
successive days, twice during the season. I?^m May 21st to 
June 21st no rain fell, and from August 22nd to Septeml)er 21st 



On Af/rindftiral Cheinisti-y, 



9 



there were only three days' rain, amounting to less than one- 
tenth of an inch. 

The following table indicates the effect of climate upon the 
qnantity and quality of the produce of the unmanured plots of 
the experimental wheat-field (during three seasons); the average 
lesults of the variously manured plots are also given : — 





1844 


1845 


1846 


Com, per acre, in boBhels, pecks, and quarters'^ 

Strair, per acre, in ponndB 

Weight of dressed com, per bnshel, in ponnds . 
Proportion of oom to straw (straw 1000) . . 


16 
1120 
58| 
824 


23 
2712 
56^ 
531 


. 17. 3. 3 
1513 
63? 
797 


Mean of all the plots — 
Weight of dressed oom, i)er bushel, in pounds 
Proportion of com to straw (straw 1000) . 


60} 

868 


56 i 
499 


63 
76.'> 



The eflfect of the climate of these three seasons, as indicated 
in this table, is qiute in accordance with the general character of 
those seasons. The lowest weight of the bushel and the greatest 
amount of straw were obtained in that season which had the 
greatest number of rainy days, and the lowest temperature ; the 
least amount of straw with the driest season, and the finest 
quality of grain in the hottest summer. On comparing the pro- 
portion of grain to straw and the weight per bushel of the corn 
obtained from the unmanured space, with the average results of 
the various experiments, it will be seen how much they agree one 
with another, and this is the more remarkable as manures of the 
most varied kinds were employed, some of which doubled the 
natural production of the soil. 

It is highly important that experiments should be tried in dif- 
ferent parts of England, having reference to the effect of climate 
upon produce. A rain gauge and a registered thermometer is all 
the apparatus required. If half an acre of the different crops on 
a farm were carefully weighed, and the relation of corn to straw, 
leaf to bulb, and the quality of grain estimated, we should in a 
few years be put in possession of sufficient data to enable us to 
roeak with certainty upon this subject. It would then be seen 
that each shower of rain and each change of temperature had an 
effect upon vegetation, which, when once ascertained, might 
always be calculated on. The farmer would be able to make an 
estimate of the quality and produce of his crops before a grain 
had been removed from his field. Even with the infomiatiou 
obtained by a careful examination of the above table, it is hardly 
to be doubted that the farmers in Scotland and in the north and 
west of England can produce turnips of finer quality and at less 
expense than those who dwell in the middle and south of EnglancJ, ; 
and that the farmer in the south of England can produce the best. / ' 

* 1844 total com, 1845 and 1846 dressed com onlj. 



10 On Agricultural Chemistry, 

corn. By the appUaition of capital and skill an artificial climate 
may, to a certain extent, be obtained. I shall point out some of 
the means to be employed when speaking on the subject of 
manures. But where equal means are employed I think a farm 
upon which there are a certain number of rainy days in the 
summer and autumn possess advantages in the production of 
green crops over another farm upon which the average amount of 
rainy days is less ; and, on the contrary, where the least number 
of rainy days and the highest temperature exist, corn of the best 
quality can be produced. The summer of 1846, with a mean 
temperature of more than three degrees above the average of the 
climate of England, having produced grain, weighing GSflbs. per 
bushel, upon any soil from which seven unmanured corn crops 
had been removed, proves undoubtedly that high iiuality of grain 
to a great extent is determined by climate indejKjndcntly of the 
action of manures. We should, therefore, expect that those 
countries enjoying a hotter and drier summer than our own would 
produce corn of superior quality, and such, indeed, is the case. In 
spite of the wTetched system of agriculture which prevails in 
Spain, Russia, Poland, and Sicily, the quality of their com will 
bear comparison with that which the skill and knowledge of the 
British agriculturist can secure. The climate of Australia com- 
bines in an eminent degree the small amount of rain and the 
high temperature necessary for the perfect development of com, 
and the wheats imported from that island obtain a price in the 
market veiy much beyond those of English growth. The follow- 
ing table gives the average climate of Australia compared with 
that of London diu'ing the summer : — 



Adelaide. 




Number of days* rain in four months 60 19 

inches „ „ 849 3-88 

Mean temperature ,, „ 60* 79 F 

Although in producing good quality of corn the farmer labours 
under a disadvantage with regard to climate in England, its low 
temperature and moisture are exactly suited for our turnip crops, 
and the advantage which he derives from this plant more than 
counterbalances the inferior quality of his grain. 

We now arrive at another important question — ^What is meant 
by quality of wheat ? Does it depend upon the weight per 
bushel, or specific gravity of the grain ? and if so, does this si)e- 
cific gravity bear any relation to the jier-centage of gluten and 
albumen ; that is to say, to the most highly nutritive constituents 
of the grain ? Before^ entering into a consideration of this subject 
it may be as well to state the opinions generally held regarding it. 
.yhe grain is composed of a variable proportion of protein com- 



On Agrkultural Chemistry, 



11 



jioniids, gluten and albumen ; and carbonaceous compounds, 
comprising starch, sugar gum, oil, &c. The protein compounds 
are employed in the organism of man and other animals in form- 
ing flesh, while the carbonaceous compounds supply heat and 
form fat. The protein compounds being of much the greatest 
importance to the animal economy, it has been generally sup- 
posed that the value of different descriptions of wheat depends 
upon the amount of gluten and albumen which they contain ; 
that the wheats of hot climates contain a greater proportion of 
these substances than our own ; that for this reason the miller 
purchases them at a higher price ; and that by employing rich 
manures the farmer is enabled to increase the per-centage of 
gluten in his com. To the agriculturist it is of little importance 
that his wheat is rich in protein compounds, unless they increase 
its value in the market. Now millers, who are his principal 
enstomeis know nothing about gluten and starch ; they judge 
by the eye alone, and give the highest price for that which will 
yield the greatest projMjrtion of flour. The following table de- 
monstrates that the value of different samples of wheat does not 
depend upon the per centage of nitrogen which they contain.* 



No*. 



Season. 



G«neral Remarks upon tho History of the 
Specimens. 



Per 

Centage of 

Nitrogen 

in Dry 

Matter. 



Price per Qr. 
accdrding to 
present rates 

adjudged 
by Miller and 
Com Factor. 



1 
2 
3 
4 



H 

y 

10 

11 

12 

1.3 



1844 
1846 



»• 






Grown by Superphosphate of Lime . . 
Ab No. 1, with ammonia Salts . . . . 

Liebig^s Patent Manure 

As No. 3, with Ammoniacal Salts . . . 

As No. 3, with Rape Cake 

As No. 3, with Bape Cake and Ammo- ) 

niacal Salts ( 

Exhausted Soil, Unmanured 

with Ammoniacal Salts 

with Rape-cake . . . 

., with Rape-cake and ) 

Ammoniacal Salts ( 

Australian, No. 1 

No. 2 

No. 3 



»i 



)> 



>} 



>> 



>» 



3 03 
2-65 
1-81 
1-69 
1-89 

1-88 

1-95 
2-01 
1-85 

1-93 



1-94 
2-38 



8. 

84 
86 
96 
92 
88 



92 
92 
92 

92 

112 
112 
112 



From this table it is evident that the samples of wheat most 
approved by the miller are by no means those which are richest 
in nitrogen. His choice is directed to those samples which have 
the character of a perfectly developed grain, small, plump, and 
thin-skinned. But laying aside the evidence of experiment or 

* The wheat employed as seed in these experiments was the Old Red 
lemmas; nearly 2 bushels were drilled per acre. The crops of 1844 and 
1H46 were sown in September, and that of 1845 in March. 



u 



12 On Affrirultural Chemistry. 

common usage, would it not be more consonant with general 
principles to suppose that a class of plants proverbially character- 
ized as yielding starchy seeds, and whose predominant peculiarity 
it is to produce carbonaceous substances, should, in their most 
perfect state of development, be rich in starch rather than in 
gluten and other nitrogenous compounds ? We might, indeed, 
expect to find the proportion of gluten and starch vary in dif- 
ferent species of wheat, and in the same species under the effect 
of different climates and seasons ; but the more perfectly the 
grain has been developed the richer in starch and the poorer in 
nitrogen it would become, and millers who prefer a perfectly 
developed grain probably pay the highest price for that which 
contains the most starch. 

That the gluten and albumen in wheat would increase in pro- 
portion to the richness of the soil and to the amount of nitrogen 
and ammonia supplied in the manure seems so reasonable a sup- 
position that its correctness is admitted without dispute ; and 
various experiments have been tried which appear to favour this 
opinion. Boussingault, in his * Rural Economy,' says, that wheat 
planted in an open field gave 2*29 per cent, of nitrogen, equiva- 
lent to 14'31 per cent, of gluten and albumen, while that planted 
in a rich garden soil gave 8*51 of nitrogen, or 21' 94 of gluten 
and albumen ; and Hermstadt obtained from wheat grown — 

In a soil mimanured ... 9 per cent, of gluten. 
In a soil manured with cow-dung . 12 ditto. 

, , sheep ditto . 22*9 ditto. 

, , bullock's blood 35 ditto. 

,, urine . . 36 ditto. 

It is not stated how the gluten and albumen were determined, 
but it is not improbable that some mechanical process was em- 
ployed ; at all events, I have great doubts about the accuracy or 
the completeness of the experiments. Thirty-five per cent, of 
gluten would be equivalent to nearly 6 per cent, of nitrogen, a 
quantity certainly greater than wheat ever contains. My own ex- 
periments do not give the slightest indication of an increase in the 
percentage of the nitrogenous constituents of wheat gi'ain by the em- 
ployment of ammoniacal manures. That the acreage produce of nitro- 
gen in the crop bears a certain relation to the ammonia supphed in the 
manure is very evident ; but the per centage of nitrogen in the 
grain cannot be increased by means of it. In some experiments, 
the quantity of ammonia supplied by the manures was from 60 
to 70 lbs. per acre, and in some instances more ; but the analyses 
give no evidence of an increased per centage of nitrogen by its 
supply, and the highest amount obtained in the series was from 
an experiment where no ammonia was supplied in the manure. 

Dr.- R. D. Thomson, in his " Experimental Researches on the 



On Agricultural Chemistry. 13 

Food of Animals," says, " It is a sufficiently remarkable fact, that 
oats increase in nutritive power in proportion to the increase of 
latitude within certain limits, while wheat follows an inverse law." 
He seems here to have adopted the prevailing opinion that the 
finest descriptions of wheat contain the most nourishment. The 
oat, which is capable of thriving in a moister and colder climate 
than either wheat or barley, would undoubtedly contain more 
nourishment when grown in high latitudes, simply because the 
climate is not favourable to the production of the important car- 
bonaceous compound of gramineous seeds, starch. But with the 
most favourable condition of soil and cUmate the grain-producing 
plants are undoubtedly governed by one and the same law. 

Although I have not at present traced the changes which take place 
during the growth of wheat, it appears to me that when sown in 
a soil containing abmidance of azotized matter it employs this 
substance at first in extending its leaf, and that where an excess 
of ammonia is supplied the production of leaf is increased to an 
extent greatly injurious to the next operation of the plant, which 
is to produce stem. If an excess of ammonia is added late in 
the spring the plant will no longer increase in leaf, but in stem 
or straw, which also may be increased to an injurious extent. 
When the azotized and mineral matters are propei^y balanced, 
the plant will produce no more of each organ than is essential to 
the favourable production of its seed. Up to the period of 
blooming the compounds of nitrogen derived from ammonia are 
probably in a fluid or suspended state, circulating through the 
whole of the plant ; but to what extent starch exists in the plant 
at this period is doubtful. \Vlien the time of blooming is passed, 
it is probable that the wheat derives but little nourishment from 
the soil, at all events, if a crop shows symptoms of poverty, it is 
always before this period. The circulating condition which has 
prevailed throughout the plant, is now changed, and under a 
favourable condition of climate (heat, light, and dryness) an 
elaborative action commences ; the compounds of nitrogen are 
withdrawn from the leaf and stem, and deposited in the seed, 
while starch is accumulated in a hard granular form. This de- 
posit of starch only takes place perfectly under the influence of a 
high temperature ; the seed is then hard, dry, and plump. In a 
cold and wet summer the interstices of the grain are not perfectly 
filled ; watery fluids occupy the place of starch, and, when these 
have evaporated, the grain is thin and shrunk. The wheat that 
is grown in a wet summer might therefore contain as high a per 
centage of nitrogenized matters dependent on the sap as that pro- 
duced during a hot and dry season. The formation and elabora- 
tion of starch and other carbonaceous compounds which for the 
most part supply man with liis respiratory or heat-producing 
elements, are, it seems, greatly favoured by a hot climate, and it is 



14 On Agrirultwal Chemistnj, 

probable that the heat capable of being eliminated by the process 
of animal respiration, must first have been rendered latent during 
the growth of the plant. 

Looking at the present state of man's existence on the earth, 
it may appear improbable that the value of com should ever be 
in proportion to its carbonaceous product. A time may arrive, 
however remotely, when the surface of the earth will be peopled 
with men very far advanced both in their moral and physical 
condition, compared with its present occupants. Bread and meat 
will then constitute the chief sources of food — ^the one supplying 
respiration, the other nutrition ; and they will doubtless bear a 
more philosophical relation to each other all over the world than 
at present. The system of cultivation in England may be con- 
sidered as tending to such a result more nearly than that of most 
other countries, and if the principles which it involves were 
properly understood and carried out, we might become inde- 
pendent of foreign supplies, even if our population were much 
greater than it is now. I have before stated that the ammonia in 
a manure is employed by grain-plants to develop carbonaceous 
products : the same principle is apparent in the economy of 
animals. Dr. R. D. Thomson, in his experiments, found that 
the cow which received the largest amount of nitrogen in its 
food produced the greatest weight of butter ; and the general 
experience of agriculturists ascribes the most fattening properties 
to those substances which contain the greatest proportion of 
nitrogen. Although ammoniacal manures favour the elaboration 
of carbonaceous matters in grain, we might expect to find a dif- 
ferent result in examining the seeds of the leguminous plants. 
The peculiarity of these plants is to produce a seed containing 
a highly nitrogenous element, called legumen. In our own 
experiments we find grain in the driest state contains one and 
two, but rarely three per cent, of nitrogen. We find in the dry 
substance of clover-seed as much as 7 per cent., and in beans and 
peas 5 per cent. The proportion of nitrogen in the seeds of 
these plants would, therefore, probably increase, within certain 
limits, under the influence of ammoniacal supply. The following 
results obtained by Dr. Gilbert seem to favour this view : — 



Beans grow-n by mineral manure . 
Beans g-rowo by ammoniacal manure 



Per ecnta^e of 

Nitropt'ii 
la Dry Matter. 




4-78 

5oy 



In the seeds of cruciferous plants, turnips and rape for ex- 



On Agricultural Cliemistry. 15 

ample, a non-nitrogenous product, oil, seems to abound, and we 
might expect that ammoniacal manures would tend to enhance its 
production in such plants, in like manner as that of starch is 
increased in the seeds of the gramineous family. Tumip-seed is 
not, however, cultivated in England with a view to its oily pro- 
due^ and I have only investigated the effect of ammoniacal 
supply upon the leaf and bulb of the plant. 

In reference to the circumstances under which the formation 
of the special product of plants seem to l)e increased, a few re- 
marks upon the cultivation of sugar-cane may not be out of place, 
especially as there are so many agriculturists in this country who 
possess property in the West Indies, and the application of 
scientific principles would increase the production of sugar and 
reduce the expense of its cultivation to an extent not very readily 
imagined. Although sugar is found in almost every plant at 
certain periods of its growth, it is only extracted profitably from 
three or four, of which the cane is the most important. Sugar 
belongs to a class of carbonaceous substances, all of which are 
developed in the greatest perfection in the hottest regions. 
Among these are starch, gum, and oil ; and although each plant 
possesses organs necessary to perfect its peculiar carbonaceous 
products, the same laws must govern the formation of them in 
all. In wheat I have shown that the carbonaceous product, 
starch, increases with a supply of ammoniacal manures, under 
the influence of a high temperature and the absence of rain ; 
owing, however, to the moisture of our climate, and the want of 
that temperature which is required for producing and depositing 
starch, there are difficulties in the way of increasing this carbon- 
aceous compound, which would not be met with if the same 
Srinciples were applied to produce sugar in the cane. If I could 
epend upon a constant climate in England similar to that of 
1846, I could produce annually 40 or 5() bushels of wheat upon 
an acre with the same facility that I now produce 83 or 34 ; but 
as it is, were I to supply the proportion and quantity of mineral 
and organic manures necessary to produce 50 bushels, in a wet 
and cold summer — it would unduly develope the circulating con- 
dition of the plant, its vascular structure would be increased to 
an injurious extent, and the crop would be laid. Those who 
farm very highly have often experienced this misfortune, and con- 
sequently they dread a wet summer. 

To the farmer whose land is out of condition, however, a wet 
summer is favourable, inasmuch as it increases the supply of 
those elemepts of which his crop is in need. In the sugar-cane 
Ihe carbonaceous product is required in a circulating conation ; 
therefore those substances should be apphed as manures which 
increase the vascular action of the plant : at the same time the 
soil should be rendered as dry as possible by draining. In soils 



16 Oti Agricultural Chemistry, 

where the elements of fertihty exist naturally, or where they are 
projDerly supplied in the manures, the richest juice and largest 
amount of sugar would be produced in the driest season. In 
the absence, however, of the proper amount of organic matter 
in the soil, the vital actions of the plant would, under the 
same climate and circumstances, be weakened. The combustion 
of the cane for fuel is a process which cannot be too much con- 
demned. It involves the necessitjr of a much greater outlay in 
manures every year ; for, if the mmeral matter which remains after 
combustion is restored at all to the soil, it is very much less 
efficacious than it would be if accompanied by the substance of 
the cane itself. In a well-regulated sugar plantation, non- 
nitrogenous products constitute the only export from the soil. 
The nitrogenous elements, which are rendered insoluble when the 
juice is heated, should be carefully removed, and either restored 
to the soil directly as manure or after being employed as food for 
animals. 

The English farmer necessarily suifers an exhaustion of his 
soil from the removal of various ingredients which have not place 
in the constitution of sugar. In grain both nitrogen and phos- 
phate are exported, both of which must be restored to the soil in 
due course. We hear of plantations which formerly produced 
many hundred hogsheads of sugar, now producing one-third the 
quantity. This can arise from nothing but exhaustion of the soil. 
It cannot be too generally kno>vn that the elaboration of carbon- 
compounds beara a very constant relation to the supply of anmnonia 
in the manure. Every pound of sugar exported, and eveiy poond 
of the cane which is burnt, involve the necessity of a supply of 
ammonia to the soil. Taking into consideration the immense 
advantage which a tropical climate affords, and the comparatively 
high price of the product, the cultivation of sugar offers advaii- 
tjiges for the profitable employment of skill and capital greatly 
superior to any that our agriculturists can hope for. It would 
however, be injudicious and improper, in defect of actual experi- 
ments, to attempt to lay down rules in detail for the application 
of a principle regarding which, as such, little doubt may be enter- 
tained. 

I now come to the action of manures, which are generally di- 
vided into two classes — on/anir and inoryanir. Although this dis- 
tinction is by no means satisfactory, I shall adopt it as being gene- 
rally under8to(xi. Organic manures are those which are capable 
of yielding to the plant, by decomposition or otherwise, organic 
matter— carbon, hydrogen, oxygen, and nitrogen— (K)nstitueufcB 
which uncultivated plants derive originally from the atmosphere. 
Inorganic manui'es are those substances which contain the mineral 
ingi-cdients, of which the ash of plants is found to consist. Most 



On Agricultural GJiemistry. 17 

of the sabstances employed as manures contain both organic and 
inorganic snbstances. The greater portion of soils consist of 
minerals in a greater or less state of decomposition, combined 
with a small amount of organic matter. Every soil is capable of 
yielding a certain amount of v^etable produce under the influence 
of climate and season, without the assistance of manure : this may 
he call^ its natural produce. The proportion would vary each 
year, according to the amount of ram, the temperature of the 
season, and the description of the growing plant. It is known, 
however, that although the climate of any place may vary one 
year as compared with another, it nevertheless maintains a certain 
average. It may be supposed therefore that the natural produce 
tif the soil, in any particular locality, would be uniform for a series 
of years. 

The effect of rain is to dissolve a certain portion of the mineral 
matter of the soil: it also suppUes carbonaceous matter and am- 
monia. Liebig found ammonia in the rain at Giessen. The rain 
collected in a vessel placed on the top of a tree in my wheat-field, 
at a distance from any building, gave, upon evaporation, a liquid 
having a foetid smell, and y^ielding ammonia to suitable re-agents. 
The rain coUected in a ram-gauge placed in a garden at Mam- 
head, in Devonshire, had the taste of soot, although the wind was 
blowing direct from the sea during its fall. Rain is therefore 
capable, to a certain extent, of supplying plants with anmionia. 
Carbonic acid is also a constant ana important constituent in rain- 
water, as well as in the atmosphere itself. The atmosphere may 
thus be considered the natural source of oi^nic, and the soil that 
of inorganic, supply. It is the object of agriculture to increase 
the produce of the soil beyond its natural yield, which can be done 
by various means. The field may be fallowed — ^that is to say, 
the natural produce of the soil for two years may be concentrated 
into one — ^the repeated exposure of the soil to the atmosphere, by 
means of ploughing, causing a decomposition of mineral matter, 
while the ammonia in the ram unites with the various acids in the 
soil. The produce of the soil may also be increased by means of 
manuresv-that is to say, by supplying those ingredients which the 
soil and the atmosphere are incapable of yielding in sufficient 
(|aantity for an agricultural result. This process I shall now en- 
deavour to explain. It will be remembered that the produce of 
wheat and straw upon the unmanured portion of my experimental 
field was ^greatest in the year when the atmospheric influence, 
and therefore the supply of ammonia, was the most ; but in no 
case was a full agricultural crop obtained. This may be attri- 
Imted to two causes : either that the wheat was incapable of assi- 
milating what the atmosphere and rain could supply, for want of 
an available amount of minerals in the soil; or that the minerals 





18 On, Agricultural Chenrntry, 

in the soil were in excess, but that the wheat was incapable of 
assimilating them for want of a sufficient supply of ammonia, or 
other organic substances. 

It has been argued by Liebig that the atmosphere can supply 
the ammonia from whicn plants derive their nitrogen, in sufficient 
quantity for agricultural purposes; and his views on this subject 
have been echoed through England by a host of his followers. 
This point, upon which so much difference of opinion exists be- 
tween the French and German chemists, is perhaps the most 
important to agriculture which chemistry can solve. It affects 
the whole economy of cultivation, and the final solution of it must 
materially influence the actions of all practical agriculturists. 
With regard to the most important crop (wheat), my own experi- 
ments are so decisive, and through the whole series the results 
are so uniform, that it is hardly possible to have two opinions on 
the subject ; and what is still more important, they are in accord- 
ance with the dictates of reason and the practical experience of 
agriculture. The first year's experiments were drawn out prin- 
cipally with the view of ascertaining how far mineral manures 
were capable of restoring to a soil, the fertihty of which it had 
been deprived by repeated cropping. On the space of ground 
which was not manured, the acreage yield was as follows : — 

Grain, 16 bushels ; straw, 1120 lbs. 
This may be considered as the natural produce of the soil, sub- 
ject only to the atmospheric influence of that particular season. 
The next experiment was with 700 lbs. of superphosphate of 
lime, which gave — 

Grain, 16i bushels ; straw, 1116 lbs. 
The superphosphate of lime employed in these experiments was 
made from calcined bone only, and was therefore strictly a 
mineral manure. By comparing this experiment with the last, 
it will be seen that practically no increase of produce was obtained. 

The effect of superphospnate of Ume upon wheat has been the 
subject of many experiments, and in some instances it has been 
employed with remarkable success. It becomes therefore of im- 
portance to inquire what was the probable cause of its inutility in 
this instance. Besides phosphoric acid and hme, the a^ of 
wheat and wheat straw contains potash, magnesia, soda, and 
silica ; and as superphosphate of lime contains none of these sub- 
stances, its failure in this case may be attributed either to the 
absence of these minerals in the soil, or to a deficiency of azotized 
or other organic matter. 

The average results obtained by other mineral manures are 
given below :• — 

* The terms Bnperphosphate of lime, phosphate of potass, phosphate of 



On Agricultural Chemistry, 



19 



Soperphoephate of liine,S50 Ibe.; phoaphateof magnesiay420 Ibe. 
Superphosphate of lime, S50 lbs.; phosphate of soda, 325 Ihs. 
Superphosphate of lime, 350 Ihs.; phosphate of potass, 375 lbs. 
Superphosphate of lime, 560 lbs.; silioate of potass, 220 lbs. 
Superphosphate of lime, 350 lbs.; phosphate of magnesia, ) 

210 lbs. ; phosphate of soda, 162| lb& I 

Superphosphate of lime, 350 lbs. ; phosphate of magnesia, | 

210 lb&; phosphate of potass, 187^ lbs. ( 

Superphosphate of lime, 350 lbs. ; phosphate of magnesia, I 

210 lbs. ; sUicate of potass, 275 lbs. I 

Superphosphate of lime, 350 lbs. ; phosphate of magnesia, 168 ( 

Ihe^; phosphate of potass, 160 lbs.; silicate of potass, 110 lbs. ) 



BoshelB 
of Grain. 



16^ 
16f 
16i 
164 

16f 
174 
17 
17f 



Foondii 
of Straw. 



1100 
1172 
1160 
1112 

1116 
1204 
1176 
1240 



The greatest increase obtained by these mineral manures over 
the natural produce of the soil was less than 2 bushels of wheat 
and 120 lbs. of straw. The effect of minerals obtained from a 
more natural manuring source (the combustion of dung), gave a 
similar result. A quantity of farm-yard dung was weighed into 
two portions, at the rate of 14 tons each per acre, one being 
bonit to ashes, and the other ploughed into the soil. The results 
were as under : — 



14 tons of farm«yard dnng . . . 
Ash of 14 tons of farm-yard dang 



Bushels 
of Graih. 



22 

16 



Founds 
of Straw. 

1476 
1104 



The absence of any agricultural increase of produce through- 
oat this series of experiments might be said to arise either from 
some defect in the mineral constitution of the manures, or from 
the minerals in the soil not being in a proper state for the wheat 
to assimilate them; but if, as is seen in the following table, the 
addition of an ammoniacal salt can produce an increase of corn 
and straw to a considerable extent, the minerals must have been 
in a state available for the plant : — 

soda, and phosphate of magnesia, by which it is convenient to designate 
the manures, are not to be understood as representing the pure chemical 
sabetances bearing those names. The composts were formed by acting 
upon bone-ash by means of solphnric add, in the first instance, in the 
caaofl of the alkaline salts and the magnesian salt, neutralizing the oom> 
pounds thns obtained by means of cheap preparations of the respective 
bases. The silicate of potass was manufactured at a glass-house by fusing 
equal parts of pearl-ash and sand — a clear transparent glass, slightly deli- 
quescent in the air, was the result ; it was ground to powder und^r edge- 
itonca 

c 2 



20 



On Agricultural Chemistry, 



1 . Superphosphate of lime, 630 lbs. ; sulphate of ammonia,65 lbs. 

2. Superphosphate of lime, 350 lbs. ; phosphate of magnesia, 

84 lbs.; phosphate of soda, 65 lbs. ; phosphate of potass, 
75 lbs. ; silicate of potass, 110 lbs. ; sulphate of ammonia, 
65 lbs 

3: Superphosphate of lime, 350 lbs.; phosphate of magnesia, . 
84 lbs. ; phosphate of soda, 65 11». ; phosphate of potass, I 
75 lbs. ; silicate of potass, 110 lbs.; sulphate of am- f 
monia, 65 lbs.; rape-cake, 154 lbs ' 

4. Superphosphate of lime, 350 lbs.; phosphate of magnesia, 
106 lbs.; phosphate of soda, 80 lbs.; silicate of potass 
110 lbs.; sulphate of ammonia, 80 lbs 



1 



Bushels 
of Grain. 



21 i 
21i 

22} 

26i 



Pounds 
of Straw. 



1368 
1480 



1768 



1772 



On comparing the produce of No. 1 in this table with that of 
the superphosphate of hme as given elsewhere, it will be seen that 
the substitution of 65 ll>s. of superphosphate of lime by 65 lbs. of 
sulphate of ammonia has caused an increase of 4^ bushels of com, 
and 252 lbs. of straw. Again, the increase shown in No. 4, 
where 80 lbs. of sulphate of ammonia were employed, is from 8 
to 9 bushels of corn, and 532 lbs. of straw, over the produce of 
the best mineral conditions as given in a former table. 

The evidence afforded in these experiments regarding the im- 
portance of ammoniacal manures caused us to discontinue the 
employment of mineral manures alone i\\ the second year. It 
was highly desirable to ascertain whether the minerals supplied 
during the first year, and also those naturally contained in the 
soil, were capable of being taken up by future crops. For this 
purpose ammoniacal salts alone were subsequently employed on 
some of the plots : — 



Season. 


Same Space of Ground each Year. 


Grain.* 


Straw. 


1844 


( Superphosphate of Lime, 560 lbs. ; silioate of \ 
1 Potass, 220 lbs 1 


Bush. Pks. qrs. 
16 1 3 


Pounds. 
1112 


1845 
1846 


Sulphate and muriate of ammonia, each 1^ cwt. 
Sulphate of ammonia, 2 cwt 


31 3 1 
27 1 2 


4266 
2244 



From the immense increase, both of corn and straw, obtained in 
the second and third years, without any fresh addition of minerals, 
it is evident that the deficient produce in the first year could only 
result from the want of some power in the plant to assimilate 
those already at its command, and that such a power was not 
wanting in the succeeding years. 

I shall only notice one more set of expriments in connection 
with this point, and which were tried in the season of 1846 with 
the wheat manure patented by Professor Liebig, and prepared 
and sold under his name and authority. On referring to the 
si)ecification of his patent, it will be seen that his object is to re- 

* 1844 total grain, 1845 and 1846 dressed grain only. 



On Agricultural Chemistry, 21 

duce the solubility of the alkalies by fusing them with lime and 
phosphate of lime, and to employ those substances which will 
fonn a compound resembling the ash of wheat : — 



J. Umnannred acre 

2. 4 cwt. of Liebig*8 wheat-manure alone 

3. i cwt of Lieblg's wheat-manure, with 4 cwt. rape-cake 
A. i cwt. of Liebig's wheat-manure, 1 cwt. each of sul- | 

phate and muriate of ammonia i 

5. 4 cwt. of Liebig*8 wheat-manure, 4 cwt. rape-cake, \ 
1 cwt. each of sulphate and muriate of ammonia ( 



Dressed Orain. 



Bush. Pks. qrs 
17 3 3 
20 1 2 
22 3 1 

29 3 
31 3 



Straw. 



Pounds 
1518 
1676 
1968 

2571 
3007 



The superiority which Liebig's manure, when used alone, ex- 
hibits as compared with the result of the unmaimred space, may 
be attributed to its containing a small quantity of ammoniacal 
matter, which was distinctly perceptible to the smell. 

The absolute necessity of supplying nitrogen to enable the soil 
to produce more wheat than it could do in a natural state, is so 
apparent throughout this series of experiments, that it is difficult 
to entertain the slightest doubt upon the subject. As long as 
any available anmaonia exists in the soil, so long will mineral 
manures increase the produce of wheat. If I had commenced 
my experiments upon a field in high condition, full of animal and 
vegetable matter, 1 might have been some years in arriving at the 
true action of mineral manures : as it was, the first year almost 
decided the question. 

For the last seven years this field has suffered an immense loss 
of minerals, rendered available to the plant by means of ammonia ; 
and the produce of last year (1846) showed that the mineral con- 
dition was still little impaired. The crop now growing shows, 
however, symptoms of an opposite condition of soil. In some 
experiments, where no minerals have been supplied, the salts of 
ammonia are not producing their accustomed enect : an excess of 
the azotized condition is commencing, and mineral manures will 
now have to be employed to increase the natural produce of the soil. 

The various contradictory results obtained by the application 
of mineral manures to wheat are completely accounted for when 
it is known that they only increase the produce in proportion to 
the available azotized matter existing in the soil. Although I 
have confined my remarks to the wheat crop, they apply equally 
lo the whole class of plants l>elonging to the same " natural order. 
Though they do not thrive equally well in the same climate and 
soil, I consider them all to Ikj plants in which the nitrogen sup- 
plied in the manure is more than what is obtained in the produce. 
They may for our present purpose be called nitrogen-consuming 



22 On AgricultKral Cfiemhtry, 

plants, in contradistinction to those which are nitrogen-collecting 
plants, and contain more of this substance than was supplied to 
them in the manure. Conmion pasture belongs to the same class 
of plants as our grain crops : hence w^e have an additional argu- 
ment to the number already advanced, in favour of breaking it up 
in every case where it is not required for ornamental purposes. 

The theory advanced by Liebig, that " the crops on a field 
diminish or increase in exact proportion to the diminution or in- 
crease of the mineral substances conveyed to it in manure," is 
calculated so seriously to mislead the agriculturist that it is 
highly important its fallacies should be generally known. The 
contempt which the practical farmer feels for the science of 
agricultural chemistry arises from the errors which ha^'e been 
committed by its professors. They have endeavoured to account 
for, and sometimes to pronounce as erroneous, the knowledge 
which ages of experience have established; and they have at- 
tempted to generalise ^vithout the practical data necessary to 
accomplisli their end with success. Agriculture will eventually 
derive the most important a^istance from chemistry, but before 
it can propose any changes in the established routine of the 
farmer, it must, by a series of laborious and costly experiments, 
explain this routine in a satisfactory manner. 

Although the experimental results which have been detailed 
undoubtedly prove that to produce agricultural cro^Ds of corn 
nitrogen must be supplied to the soil in some form or other, 
two important questions still remain unanswered, namely, first, 
what amount of ammonia will Idc required to produce a given 
amount of com ? or, in other words, what amount of nitrogen 
must the farmer accumulate in his soil to obtain each bushel of 
com l>eyond the natural produce ? Secondly, what are the most 
economical means at his disposal for securing the necessary 
supply ? The solution of these questions is >vithin the reach of 
careful exj^eriment and calculation ; and, although any data at 
present at our disposal may be incompetent to a proper' treatment 
of them, it may serve some useful purpose to apply such results 
as we possess with tlie view of arriving at some general and ap- 
proximative knowledge on points bearing so essentially on the 
economy of agriculture. 

It may be considered for our present purpose that a bushel of 
wheat contains one pound of nitrogen. It must not be supposed, 
however, that 1^ lb. of ammonia (equivalent to one pound of 
nitrogen) supplied to the soil, will, even under the most favour- 
able circumstances, add a bushel to its natural produce. Through- 
out the whole course of my experiments upon the growth of 
wheat by means of ammoniacal salts there nas been a loss of 
nitrogen far too great to be attributed merely to drainage and 



On Agricultural CJiemishi^. 23 

evaporation from the land ; and it is possible that a better know- 
ledge than we now possess of the vital actions of plants will, 
sooner or later, throw much light upon this interesting and highly 
important phenomenon. I am inclined to think that, for prac- 
tical purposes, we may assume 5 lbs. of ammonia to be required 
for the production of every bushel of wheat beyond the natural 
yield of the soil and season ; at any rate, it will be useful to re- 
member this as the amount until further experiments shall furnish 
farther information on the subject. In the following table, p. 24, 
are arranged some of the results obtained last year (harvest, 1846) 
in my experimental wheat-field. 

B^id^ the bearing which these results have upon other points 
tlian that of the amount of ammonia reouired to produce a bushel 
of com, they will enable any one to judge of the probable exact- 
ness of the estimate which has just been made. It should be 
remembered, however, that as the season of 1846 was more than 
Qsnally favourable to the production of corn, anv calculations 
founded upon the results of that year might lead, to an over- 
estimate of what the anmionia would produce in an average of 
years. The produce of the unmanured plot and that of farm- 
yard dung was, in dressed grain and straw, as follows — 

Bnsh. pks. qrs. Straw in lbs. 

No manure . 17 3 3 1613 

14 tons of dung . 27 8 2454 

It was my intention to conclude this paper with some experi- 
mental evidence relative to the influence of climate and manures 
upon the turnip and leguminous crops ; but, having extended my 
obser^'ations upon the corn-plants to a greater length than I had 
at first contemplated, I shall defer the consideration of that 
subject to a future period. I wish, however, to make a few ob- 
ser\'ations upon the general principles of practical agriculture. 
Some of them are apparent from the evidence I have already 
brought forward, but some of them are indicated by the results 
of other branches of the investigation than those which I have dis- 
cussed in the foregoing pages. 

I have said that soil and atmosphere are the two great natural 
sources from which plants derive the elements of their growth; 
the former supplying the inorganic and the latter the organic 
elements. Besides the minerals of which soils are principally 
composed, they contain a certain amount of organic matter ca- 
pable of yielding carbon and ammonia to plants; and the annual 
amount of ammonia which a soil is competent to yield under the 
influence of the atmosphere must to a certain extent determine its 
natural fertility. A Russian soil, said to be one of the most fertile 
in the world, and which yields fine wheat without manure, gave 
when analysed by M. Peyen, 24j lbs. of nitrogen in 1000 lbs. of 



On Agricultural Cliemislry, 



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On Agricultural Clmnistry, 27 

soil, or nearly 2^ per cent. A very fertile soil sent to me by Sir 
John Tylden from Somersetshire, and said to yield 40 bushels 
of wheat annually without manure (a statement afterwards proved 
to be incorrect), was analysed by Dr. Gilbert in my laboratory, 
and gave 6'2 lbs. of nitrogen in 1000, or rather more than ^ per 
cent. ; whilst from the soil of my experimental field, which yields 
about 17 bushels of wheat annually without manure, he obtained 
in 1000 parts only 2*0 of nitrogen, equal to l-5th per cent. 

Although the amount of nitrogen in a soil, indeixjndently of any 
immediate supply, may determine to a certain extent its powers of 
producing com, it is not a sure criterion of the value of different 
descriptions of soil. The rich clayey soils, in which the largest 
stores of nitrogen are generally round, are exactly those which 
derive the least benefit from a rotation of crops. The amount of 
nitrogen existing in a sandy soil may hardly be appreciable by 
analysis, but by the free circulation of air through its pores, the 
accumulation from the resources of the atmosphere through the 
medium of green crops, and especially of turnips, to a certain ex- 
tent counterbalances the deficiency. The actual value of a tur- 
nip crop must vary very much, according to the texture of the 
soil On heavy clays, the decomposition of soil by means of a 
snmmer-fallow aided by lime, will often render available more 
ammonia as well as mineral mixtures, than could be obtained by 
means of a turnip-crop. Upon light soils, however, nothing can 
advantageously substitute the collective powers of the turnip. In 
one soil the accumulation of available stores may be affected by 
combustion or hme, iu the other they must be supplied by a dif- 
ferent process. As almost every soil contains mineral matter in 
an undecomposed state, it must evidently be advantageous to 
favour its liberation by every possible means ; for the more pro- 
duce a soil can be made to yield without manure, the less manure 
it will require to bring its produce up to a maximum. It was at 
one time supposed that by repeatedly hoeing and stirring the soil, 
it could be made to yield perpetual crops without manure; and 
although this was carrying the principle too far, it undoubtedly 
proves the benefit of mechanical operations. Draining, however, 
offers advantages to the agriculturist superior to any as a means 
of obtaining the influence of the atmosphere upon the soil. Not 
only is the surface of the soil exposed to the action of the air, but 
its influence extends to the depth of the drains themselves. In 
addition to this advantage, what may be considered as an artificial 
climate is to some extent obtained. An increased temperature, 
and the absence of moisture, conditions so essential to the pro- 
duction of grain of fine quahty, are the result of draining the soil. 
Thermometers placed in two soils equally exposed to the sun's 
rays, one of which is moist and the other dry, indicate very differ- 



28 On Agrkultural Ctiemktry, 

ent degrees of temperature. The rays of the sun, which only serve to 
evaporate moisture in the one, will raise the temperature of the other. 
It follows that plants would grow more rapidly upon a well-drained 
soil than upon one in an opposite condition, especially during the spring. 

It will be remembered how large a quantity of ammonia 
I found it necessary to supply to my soil each year to 
restore the substances removed in the pre^ious crop. Besides 
being expensive, this ammonia cannot be procured in the 
market in any large quantities ; but by cultivating turnips and 
the leguminous plants, a large amount of this substance is col- 
lected by them from the atmosphere. A rotation of crops ma^ in 
one sense therefore be considered as an economical process for 
obtaining ammonia; but as the amount obtained by green crops 
must depend very much upon their bulk, every attention should 
be paid to their growth. In order to produce the great- 
est weight of turnips, it is necessary that the soil should be 
brought to the finest and lightest condition possible by mechani- 
cal means, and that it should be manured by a large and available 
supply of carbon and phosphates. Ammonia artificially supplied 
is not essential if the soil be not deficient in carbonaceous sub- 
stances ; and where the phosphates are not supplied in sufficient 
quantity it exerts a most injurious effect upon the plant. 

The turnip is essentially a plant which requires artificial aid 
for its development in agricultural quality and quantity. It is 
singular that while my soil yields 17 bushels of wheat annually, 
without manure, the turnips upon an unmanured space were re- 
duced to a few cwt. per acre in three yeare, and in the fourth 
only averaged the size of a radish. It is also remarkable that a 
plant whose office it is to restore fertility to the soil should 
scarcely be able to exist where wheat was yielding a tolerable 
crop ; but the different effect produced upon two crops by fann- 
yard dung and superphosphate of lime at once explains this 
anomaly. Eighty-four tons of farm-yard dung, consisting of de- 
caying straw mixed with the excrement of the ifarm-horses, applied 
to one acre of wheat and one of turnips during three years, at the 
rate of 14 tons per acre per annum, did not, in the acre of wheat, 
add much more than one-half to the natural produce each year : 
the turnips, however, were increased to an indefinite extent. 
Superphosphate of lime, which produced no increase of wheat the 
first year it was applied, gave in succession three good crops of 
turnips. The dung which I applied to my wheat increased the 
produce to an extent equivalent to the amount of ammonia which 
it may be estimated to contain ; but it is evident that the great 
bulk of 42 tons served little useful purpose, for we find that 
salts of ammonia have produced each year a larger amount of 
corn. The whole of the solid matter of the residue, consisting of 



On Aff^ri/niltuy-al Chemistry, 29 

organic matter almost destitute of nitrogen, could have been 
aBsimilated by the turnip, under the influence of a due supply of 
phosphates. On poor soils it is quite consistent with scientific 
principles to employ rich azotized dung for the wheat crop, and 
to convert the carbonaceous residue into the substance of the 
Uimip by an abundance of phosphates. It would, however, pro- 
bably be advantageous to have a greater proportion than one- 
fourth of the farm under turnips each year. At present, upon 
the Norfolk-system one-fourth of the farm is clover, but broad 
clover cannot be obtained with certainty so often. If instead of 
this, one-eighth of a farm was clover and three-eights turnips, 
a larger proportion of winter food would be obtained, and as 
much clover grown upon an eighth as has hitherto been grown 
upon one-fourth of the farm. We have no reason to suppose 
that one grain crop possesses the power of exhausting the soil 
more than another. The tenant-farmer should therefore be per- 
mitted to grow that crop which is most suited to his soil. On 
tiie heavy soils alternate wheat crops might be grown ; oats might 
also be substituted for barley >vith advantage, whenever the soil 
has been rendered incapable of complete pulverization, by con- 
suming the turnips upon the land in wet weather. 

Ha\ing, I trust, shown upon scientific principles that a rotation 
of crops is indispensible in order to carry out a system of prac- 
tical and economical agriculture, I shall now endeavour to prove 
by a few brief observations that to obtain the greatest possible 

Sroduce from the soil, the production of meat ought to bear a 
efinite relation to the amount of grain exported. 
The philosophical considerations to which this subject naturally 
leads are of the highest interest ; but as it would be impossible to 
treat of them at once clearly and at the same time as briefly as 
our present object permits, it will be best to turn our attention to 
some of the more practical bearings of the question. 

In feeding stock but a small proportion of the nitrogen in the 
food is converted into the substance of the animal; the greater 
portion is restored to the soil as manure. The economy of the 
production of meat as a means of obtaining manure arises from 
the greatly increased value of the nitrogen in flesh, as com- 
pared with that supphed in the food. Thus 28 lbs. of flesh, worth 
14«., contains 1 lb. of nitrogen — 28 lbs. of peas, beans, or oil-cake, 
which contain about the same quantity, are not worth more than 
2*. or 8«. To determine the exact proportion of the meat, or 
rather the live weight of stock which must be produced upon any 
farm to obtain the greatest possible produce of grain, requires a 
long and careful series of investigations. 

With the exception of one experiment performed by Boussin- 
ganlt, we have no data from which we can calculate the loss of 



30 On Agrkultural CJiemisiry, 

carbon and nitrogen which a farm sustains by the vital proceases 
of the animals fed upon it, but it is evident that it is most serions. 
In Boussingault's experiments it appeared that a cow respired in 
24 hours as much dry organic matter as was equivalent to 
100 lbs. of turnips. This forms a strong argument in favour 
of the modern system of fattening animals rapidly by means 
of artificial food. When turnips are plentiful and stock \& 
dear, farmers not unfrequently give their turnips to any person 
who will bring stock to consume them. And it is a common 
practice in some places to feed a quantity of half-starved 
cattle upon straw for the purpose of converting it into dung. It 
should, however, l)e understood that the passage of the straw 
or turnip through the stomach of the animal, far from adding to 
the quality of these substances as manure, abstracts a large pro- 
portion of their valuable elements. There is no magical property 
in the black mass called dung which did not exist in the straw. 
Some of the elements may be rendered more rapidly available 
by the decomposing agency of the animal ; but the actual quan- 
tity restored to the soil must be considerably reduced. In all 
cafies, therefore, where artificial food is not employed, or when 
the consumption of food is not attended with profit, it is better to 
restore the superabundance of green crop more directly to the 
soil for the after-growth of corn, whilst any residue of our com 
crops, if it cannot be used as litter, will, if returned to the soil in 
its natural state, or after suffering decomposition between layers 
of earth, supply constituents to the succeeding fallow crop. 

The increase of meat obtained by any particular food must 
vary to a certain extent, with animals of different breeds and ages, 
a£ well as with the care and attention bestowed upon them. There 
is, however, in all cases, a relation sufficiently evident, between 
the increase of the animal and the nitrogen in the food, to enable 
us to form some calculation upon the relation which should exist 
between the production of com and that of meat upon a well 
cultivated farm. In illustration of this statement, in the first 
place I may refer to some experiments made upon the farm of 
the Earl of Radnor, regarding the feeding qualities of different 
breeds of sheep. The results are quoted from the last number of 
this Journal. 

In the 1st experiment, 20 sheep received 847 lbs. of hay, 
1319 lbs. pulse, and 25,293 lbs. swedes, and the increase of live 
weight was 400 lbs. In the 2nd experiment 1044 lbs. of hay, 
and 17,254 11)8. of turnips produced 192 lbs. of increase. Calculating 
the nitrogen consumed by the first lot, to be in hay 8^ lbs., 
in the pulse 45 lbs., in the turnips 38 lbs., aMd taking the per 
centage of nitrogen in the increase of live weight at 3^, we have 
in the first experiment — 



On Agricultural Chemistry. :^1 

91i lbs. of nitrogen supplied in the food. 
14 lbs. do. converted into increase. 

Upon similar calculations the 2nd experiment gives — 
35 lbs. of nitrogen supphed in the food. 
7 lbs. do. converted into increase. 
In the firet experiment 1 lb. of nitrogen produced 4^ lbs. in- 
crease of flesh, and in the 2nd, 1 lb. of nitrogen produced 5^ lbs. 
increase ; not making any allowance for the probable loss by the 
vital processes of the animals, and in the preparation of the dung, 
we have for each pound of nitrogen exported, as much in the first 
experiment as 6^ lbs. ; and in the 2nd, 5 lis. remaining for ma- 
nure. 

In the * Gardeners' Chronicle,' for the year 1844, are given 
the results of some eiroeriments u^n feeding sheep conducted 
upon the farm of the Earl of Ducie, by Mr. Morton ; some of 
these sheep were fed in the field, some under cover. Altogether 
25 sheep were experimented upon, and they increased 611 lbs., 
having consmned 31,580 lbs. of swedes, 2775 lbs. of oats. Calcu- 
lating the food to have contained 95 lbs. of nitrogen, and the 
increase of live weight to represent 21 lbs. of nitrogen, 1 lb. of 
nitrogen produced 6j lbs. of live weight, and for each pound of 
nitrogen exported in meat, 3^ remain for manure. 

In an experiment of my own, two pigs which consumed food, 
containing by analysis 12^ lbs. of nitrogen, increased in weight 
71 lbs. This gives nearly 5 J lbs. increased live weight for 1 lb. 
nitrogen in food, and for every pound of nitrogen exported in 
increase about 4 lbs. remain for manure. 

In Bacon's Essay on the Agriculture of Norfolk, there is a 
table of the feeding qualities of oil-cake and swedes, compared 
with a compound of boiled Unseed with peas and swedes ; six 
oxen were selected for each trial, and the live weight of each 
beast was taken at the commencement and the end of the experi- 
ments. 

The following are the results : — 

1. — 6 oxen consumed 106,792 lbs. turnips, 3,712 lbs. peas, 
1,110 lbs. linseed. 
The increase of the hve weight being 1,722 lbs. 
2. — 6 oxen consumed 108,440 lbs. turnips, and 6,183 lbs. 
oil-cake. 
The increase of the live weight being 1,310 lbs. 
In the 1st lot the nitrogen in the food was about 335 lbs., 
1 lb. of nitrogen gave 5 lbs. of increase in live weight, and for each 
pound of nitrogen exported 4^ llis. remained for manure. 

In the 2nd lot, the nitrogen in the food was 389 lbs., 1 lb. of 
nitrogen gave 3-j^ increase, and for each pound of nitrogen ex- 
ported 7i remain for manure. 



82 On Agricultural Cliemistry. 

In consequence of tumip being employed as part of the food, 
in all the results which I have given, it is impossible to make any 
calculation respecting the economy arising from fatting cattle as a 
means of obtaming manure, without first deciding at what expense 
turnips can be produced. Upon this subject very great difference 
of opinion exists amongst agriculturists, and indeed the effects of 
soil and season so materially affect the question, that it is scarcely 
safe to make any calculations respecting it. Some would value 
them as low as Is. per ton, some as high as 20s. 

By the kindness of a friend, however, I have been provided 
with some results obtained by feeding upon marketable food 
alone. As the results extend over a considerable number of 
years, in each of which 30 to 40 oxen were fattened, they may be 
considered to afford very trustworthy information on the subject. 

Each ox received for 22 weeks 20 lbs. of the best clover hay, 
and 10 lbs. of English oil-cake per day. They sold for 9/. more 
than they cost, and the average loss upon each was 4/. 12«. 

Each ox received 8080 lbs. of hay = nitrogen 49 lbs. 

1470 lbs. oil-cake do. 70 lbs. 

Total nitrogen 119 lbs. 

Estimating the increase in live weight according to the increase 
in money value at 576 lbs., and the nitrogen to amount to 3^ per 
cent, of their weight, we have 20 lbs. of nitrogen in the increase. 

1 lb. of nitrogen gives nearly 5 lbs. of increase live weight, and 
for each pound of nitrogen exported 5 lbs. remain for manure. 

99 lbs. of nitrogen remaining for manure are equivalent to 
120 lbs. of ammonia. 

To supply the 120 lbs. of ammonia in Peruvian guano of 
average quahty, it would certainly require more than half a ton of 
that manure, which at the present time would cost bl. The price 
of ammonia thus obtained would be lOrf. per lb. 

In my experiments upon wheat, it required 5 lbs. of ammonia, 
to produce a bushel of corn. To obtain this amount of ammonia 
by means of stock, there should be an increase of about 28 lbs. of 
live weight upon the farm ; or in round numbers, to obtain 1 ton 
of grain beyond the natural production of the soil, there ought to 
be an increase in the weight of stock of 1000 lbs. In order to 
bring an exhausted soil to the highest state of fertility, it will be 
necessary to produce an amount of meat by means of imported 
food (such as hay and oil-cake) as will be equivalent to the in- 
crease of grain required. As the green crops increase year by 
year, the same amount of meat will be produced, but the importa- 
tion of artificial food mil gradually decrease to the point at which 
the internal and external resources of the farm are so balanced as 
to secure the largest amount of produce from the soil. 



On Agricultural Chemistry. 83 

I have not tried the comparative feeding qualities of the leaf 
and the hulb of the tnmip; but from the mnch higher per 
oentage of nitrc^en in the former, as determined by analyses in 
my laboratory, it may be inferred that it is much more nutritive. 
This would be the case more particularly with the late-sown 
tomips, when the circulation of the fluids in the leaf is still 
active, and the plant has not had time to produce a full-sized 
bulb. It is possible, however, that the relatively low state of 
elaboration of the constituents of the leaf might interfere with its 
otherwise apparent applicability as a healthy focKl. 

According to the rule winch has been assumed — ^namel^, that 
the production of 1000 lbs. of live weight increases the yield of 
grain by 2240 lbs. — ^the production of 576 lbs. of live weight, as 
in the cases of the oxen cited above, would give 1290 lbs. increase 
in grain, equal to 21 bushels of wheat. 

This method of fattening bullocks may be considered as the 
most expensive the farmer can adopt. The whole of the food 
employed (hay and oil-cake) may be viewed as manufactured 
articles : it is evident, nevertheless, that artificial manures would 
have been a dearer source of ammonia than that afforded by the 
feeding of the animals ; but when the other constituents of the 
several manures are taken into account, the balance will be still 
more in favour of the fattening process. The drv matter contained 
in the food of the ox was nearly 4000 lbs ; and of this quantity, 
deducting the Uttle that was converted into the substance of the 
animal, the only remaining reduction, if the dung be properly 
manufactured, is in the carbon respired by the animal, which, 
under the system of agriculture here advocated, is a consideration 
of no moment. It may appear to some agriculturists that I have 
entered into details on this subject which are both tedious and 
unnecessary, but I would solicit a careful consideration of them. 
I do not at all imagine that the precise relations of ammonia to 
increase of com, and of nitrogen in food to nitrogen of live weight 
obtained, are really such as have been assumed for the purposes 
of illustrating the views advocated in this paper. My object is to 
establish as a principle, by which practical agriculture should be 
guided, that the amount of meat or live weight of stock produced 
upon a farm, should bear a fixed relation to the quantity of com 
exported. 

If the tmth of this postulate be once established, and the proper 
proportions fixed, it will no longer be necessary to enforce upon 
the farmer any particular rotation of crops. So long as a due re- 
lation between his production of meat and export of com were 
maintained, there would be no fear of an exhaustion of the soil, 
even if he grew no green crops whatever ; and he might safely 
be left to make his own choice of the means he would adopt. 

D 



34 On Agricultural Chenusiry, 

His object being the prodnction of a certain amount of meat at 
the lowest possible expense, he would naturally devote his ener- 
gies to the production of large green crops, in order to limit his 
outlay in artificial food. Knowing, too, the most profitable con- 
ditions upon which his com could be raised, his chief attention 
would be paid to the economical supply of food for his stock, in 
full confidence as to the consequences of his course. 

In objection to any rule which may assume a neoeseary relation be- 
tween the production of meat and that of com, it may be maintained 
that were any cheap and inexhaustible source of ammonia discovered, 
the production of meat, as the means of exporting com, should be 
materially lessened. The diflBculties, however, which we may 
fairly calculate upon as standing in the way of such a consumma- 
tion, as well as the physiological and commercial considerationB 
which would be involved in its influence, are such that we need 
not now anticipate the result. Again, the supposition that the 
artificial manures at present at our command, might, if directly 
applied to the growth of com, be adequate to its sufficient pro- 
duction throughout the country, without the aid of green crops 
in feeding, is satisfactorily met by such calculations as the fol- 
lowing : — The county of Norfolk is said to comprise 1,888,880 
acres of land : suppose one-half of this to be cultivated on the 
four-course system, 334,720 acres will be under com every year. 
I beheve it will not be considered an exaggeration to say that 
cultivation in this county has increased the natural produce of 
com by 10 bushels per acre ; and according to my calculations, it 
would require something like 50 lbs. of ammonia to be supplied 
in any artificial manure to produce this increase of com ; and 
considering 1 ton of Pemvian guano to contain 224 lbs. of am- 
monia, it would require an importation of 74,714 tons to supply 
the necessary amount for one year. This calculation affords some 
idea of the value of a rotation of crops. 

It is not very difficult to arrive at a correct knowledge of the 
action and value of artificial manures. They are generally com- 
posed of two or three ingredients in a state of concentration, and 
are far more rapid in their action upon plants than the manure 
which is produced by animals. They can therefore be applied 
with greater success to those crops which are required in an arti- 
ficial condition, and the growth of which cannot be too vigorous. 

If there be any tmth in my experiments, all hope of obtaining 
annual crops of com by means of mineral manures must for 
ever be abandoned. The employment of potash, soda, magnesia, 
and silica, has been suggested by chemists, from an imperfect 
knowledge of practical agriculture. Having found these sub- 
stances in the ash of the puints, they have concluded that the soil 
cannot supply them in sufficient quantity. I could bring forward 



On Agricultural Chemistry. 85 

a great number of experiments, tried at my suggestion upon 
variona soils, which would prove that alkaline manures were quite 
incompetent to remedy the exhaustion from which they suffered; 
but the general practice of the best agriculturists is more con- 
viiicing than a thousand such experiments. Take the case of a 
soil which has been in the hands of a farmer who has removed 
from his land successive grain crops, and who has also sold part 
of his straw and hay, bringing back perhaps a little soot, or some 
light manure. This system would exhaust the soil of its alkalies 
to the greatest extent possible. Should it then come into the 
posBe8Bi<»i of a man of capital and experience, he may in a few 
years bring it into high condition without imparting to it a pound 
of potash or soda, though the course he would probably adopt 
would indirectly increase the available sources of those sub- 
stances. 

The quantity of alkahes taken up from the soil by a crop of tur- 
nips is very great, and yet the artificial manures most commonly 
applied to grow these turnips contain but little and often no alkalies 
whatever. As long as bone-dust, superphosphate of lime, or guano, 
will produce a good crop of turnips, the farmer need be under no 
apprehension of his soil being destitute of alkalies. The only 
mineral which, under a proper system of agriculture, it is neces- 
sary to restore directly to the soil, is phoGphate of lime. Where 
lai^ breeding flocks are kept, the phosphate of hme exported in 
the bone of the animal is very great, and man^ soils are incapable 
of jrielding this in sufficient quantity. Previously to the intro- 
duction of guano into this country, large quantities of nitrate of 
potass and soda were employed as manures. Their value was, 
by many persons, attributed to the alkahes they contained ; but 
t£e almost universal substitution of guano shows very clearly that 
the potash and soda were not the constituents to which their 
effects were due. At one time I thought it probable that the 
silicates of potash or soda might prove of some service to grain 
I^antB, but repeated experiments with these substances have 
caused me to alter my opinion. 

The strength of the straw in grain crops seems to depend upon 
a healthy condition of the plant, arising from a properly balanced 
supply of mineral and oi^nic constituents, as well as upon the 
influence of certain physical conditions of soil, especially during 
the early stages of growth. Thick sowing, a cold wet summer, 
and excess of ammonia, are all injurious to the strength of 
stfaw. 

Unless straw is sold, there is a constant accumulation of silicate 
of potash upon farms, arising from the annual decomposition of the 
soil ; and upon some farms the production of straw increases to an 
injurious extent. It is a common opinion, that artificial manures 



86 On Agricultural Chemistry. 

act as stimalants, and that the continual emplo3rment of them 
tends to exhaust the soil. This idea is to a certain extent correct ; 
and where they are used injudiciously (as, for instance, when a 
mineral manure is employed upon corn crops) it would lead to 
such a result. But it they are employed to increase those crops 
which are consumed upon the farm, such as turnips and clover, 
they then become valuable aids to the natural resources of the 
farmer. 

To obtain agricultural crops of clover, tares, and tumips, 
purely artificial conditions of growth, quite at variance with the 
natural tendency of the plant, are induced : and it is well known 
that the crop of clover which will yield the most hay is by no 
means that which would be selected for seed. These conditions 
are secured by an artificial supply of certain elements favouring 
the desired determinations of the plant ; and therefore artificial 
manures may for such purposes be employed with advanta^. 

If grain crops, as I have endeavoured to show, can be grown 
at a cheaper rate by the production of meat, than by the direct 
action of artificial manures, the propriety of adopting the former 
course to its full extent becomes simply a question of capital. It 
would require five times as much capital to produce the same 
amount of com by means of stock as could be produced by arti- 
ficial manures. It is the same with the manufacturer who em- 
ploys a high-pressure or a double-cylinder engine ; with the 
former his capital invested is small, but the interest ^id upon it, 
by the daily consumption of fuel, is very great, while with the 
latter his invested capital is large, and his daily interest compara- 
tively small. The want of sufficient capital among so large a 
portion of our agriculturists cannot be sufficiently deplored in a 
national point of view. They imagine that the greater extent of 
land they can farm with a limited capital, the greater will be the 
interest obtained for it ; by which means the amount of labour 
employed is reduced to the smallest possible extent. High prices 
have hitherto allowed a system of agriculture to be pursued, by 
which little more than the natural prince is obtained from the 
soil. But if the average price of com should ever be reduced to 
the standard of other countries, a reduction of rent must take 
place equivalent to this diminution, or the decrease in the value 
of corn must be balanced by an increased average produce from 
the soil. 

J. B. Lawbs. 
Rothamated, 



London: Re-printed by Dukk & CHiDOsr. 156 and 167, Klngsland Road, E. 



ON 



AGRICULTUEAL OHEMISTEY. 



TURNIP CULTUEE. 



By JOHN BENNBT LAWES 



LONDON: 
PRINTED BY W. CLOWES AND SONS, STAMFORD STREET, 

AMD CEABZMa CB088. 

1847. 



SEPRINTED BT SPOTTISWOODE A CO., NEW-STREET SQUARE. 

1896. 



FROlf THB 
JOUBNAL OP THB ROYAL AUBICULTUBAL 800IBT7 OF BNOLAND, 

VOL. VUL, PABT IL, 1847. 



NOTE ON REPRINTING IN 1896. 

This paper, which was published in 1847, now nearly fifty 
years ago, records experimental results and condnsions which are 
still of interest and importance ; but there are some points to 
which it seems desirable that reference should here be made. 
Thus, it is throughout assumed that the carbon of the '' orgame '* 
manures used, such as &rmyard manure, rape-cake, &c., was an 
important source of the carbon of the crops, but it is not now 
supposed that it is so in the case of chlorophyllous vegetation. 
Independently of the benefits arising from the mechanical effects 
of farmyard manure, such '' organic " manures are specially 
valuable for the nitrogen and the mineral matters they supply ; 
the carbonic acid yielded on the decomposition of their carb<m- 
aceous constituents being chiefly useful in aiding the solution of 
the mineral constituents of the soil or the manures. The nomen- 
clature is also in some cases not such as would now be used. 
For example, the turnip is throughout called a " bulb," instead 
of a root, as it is more properly designated. 



r" 



AGKICULTUKAL CHEMISTEY. 



TURNIP CULTURE. 



ExPEmEHGE is a legitimate and trustworthy guide in all the 
great practical arts affecting the physical condition of the human 
race, and, for agriculture, as for many other branches of industry, 
has attained a considerable degree of progress independently of 
the aid of science ; but in so far as experience, as distinguished 
from principle, is relied upon, must we be content that the soundest 
practices should only be adopted by that small proportion of the 
entire masses who exercise an intelligent observation, and have 
arrived at rules for future guidance more or less by the lessons 
of past error. But although the results of investigation into the 
rationale of well recognised practices should prove them to be in 
the main consistent with philosophy, rather than show them to 
be fundamentally erroneous, yet, when it is remembered that a 
well understood and simply explicable principle is much more 
easily acted upon and by a much greater number of individuals 
than are the dictates of the most acute empiricism, the claim of 
science as an improver, as well as an exponent of the economic 
arte, must be fully admitted. The young man of average talent 
and education, by the assistance of principle, attains comparatively 
early the position which otherwise half a life is spent in seeking. 
Granting, however, what we are by no means called upon to do, 
that the best practices of the age are beyond the aid of science, 
and that their more current adoption rather than their improve- 
ment is to be expected, a better knowledge than is now prevalent, 
regarding the first principles of vegetable growth, will serve to 
protect the farmer from the many snares into which either fraud 
or ignorance would lead him. If, then, the results of investiga- 
tion should tend to explain and to enforce good old practices, 
Tather than to put forth those which are new and untried, the 

B 2 



4 Agricfidtural Ghemisfrij — Tuniips. 

utility or even the necessity of the application of science to 
the improvement of oar national agricaltore will not be the less 
evident. 

The question with the agricnltnrist is not so much what are 
the constituents which must exist in his soil for the growth of a 
given amount of produce ? but what constituents or class of con- 
stituents does this or that crop exhaust, relatively to another con- 
stituent or class of constituents ? Looking at the subject in this 
point of view, we are of opinion that the increased growth of 
com may be considered to have a very intimate relationship to the 
amount of nitrogen supplied to the soil : and since, owing to the 
scarcity and high price of ammoniacal salts, or other direct nitro- 
genous supplies, it is impossible to rely upon these sources, a 
rotation of crops, and the importation of food for stock, come to 
be not merely the only generally applicable, but the most econo- 
mical, means of restoring fertility to the soil. Under snch a 
course for the special accumulation of nitrogen, it will be found 
that there is always secured an abundant coincident supply of 
mineral and carbonaceous substances, and hence the direct im- 
portation of these latter substances is seldom necessary. 

The results of our experiments upon wheat and other plants of 
the gramineous family have indeed shown, beyond a doubt, that 
the character of the exhaustion which the soil suffers by their 
growth is essentially and pre-eminently nitrogenous ; and since 
common usage bears ample testimony to the efficiency of alter- 
nate cropping, it is to be supposed that an examination into the 
composition, habits, and sources of growth of the plants which 
enter into a rotation, would bring to view important functional 
differences and peculiarities in the different plants, and such as 
should give confidence in general principles and tend to im- 
provement and economy in practice. 

The greatly varying form and appearance of the various agri- 
cultural plants, implying, as undoubtedly they do, essential 
differences in their sources of nutriment, have led, from but 
superficial observation of them, to erroneous assumptions regard- 
ing the true office of certain plants in a course of agricultural 
cropping. Thus it is by some maintained that the large surface 
of leaf put forth to the atmosphere by the turnip, taken in con- 
nexion with the general character and utility of the crop, be- 
speaks an almost exclusive reliance upon the natural resources 
of the atmosphere for its carbonaceous supply ; and the direct 
application of nitrogenous manures has accordingly been recom- 
mended witji the view of favouring to the greatest extent the 
development of leaf as a means of securing bulb. 

Again, agricultural plants have been arranged according to 
their botanical alliances ; and distinctions between the necessary 



AffriouUural Chemistry — Turnips. 5 

conditions of ai-tificial supply of certain constituents have been 
made, which are inconsistent with the dictates of experience, and 
equally so with those to which we are led when other circum- 
stances besides the (nevertheless important) botanical distinctions 
are brought into consideration. The varying quantitative reliance 
ufK)n the atmosphere and the soil of different natural families of 
plants constitutes indeed a most interesting and important point of 
study, and the principles upon which the tiatural system is founded 
may derive essential confirmation from chemical researches ; but 
in referring the varying agricultural value of different plants to 
the functional characters of the several natural orders to which 
they belong, it must always be first decided that the natural aim 
and tendency of the plant and order are favoured by our methods 
and objects of cultivation, and that the agricultural value of 
the phmt is in no way dependent on a monstrous or artificial 
development at variance with that of its individual health and 
reproductive tendencies. 

The cultivation, habit, and uses of the tuniip are well suited to 
form a contrast to those of our grain crops ; and the plant itself 
may, to some extent, be taken as the type of the green or fallow 
crops, a main effect of which is the preparation of the soil for the 
after-growth of com. The essentially artificial condition which 
is induced in the cultivation of the turnip plant, for feeding and 
manuring purposes, is most strikingly illustrated by the effect 
of climate and manures upon the quantity and composition of 
the produce. 

We shall now proceed to discuss in detail the results of ex- 
periments which have been in progress in the field and in the 
laboratory for several years, and which were undertaken with the 
view of elucidating some of the general effects of rotation. From 
the commencement of the inquiry it has been our wish to avoid, 
as far as possible, the bias of any of the conflicting opinions 
which have of late years been put forth upon the important 
subject under examination, and it will be our endeavour, as we 
proceed in our Report, impartially to lay before our readers such 
results of direct experiment as will enable them to form their 
o?ni estimate of the soundness of any views which we may 
advocate or adopt. 

At the outset, however, it may be well to caution the agricul- 
turist against expecting what we by no means presume to exhibit. 
The object of the experiments has not been the production of 
immense crops, but to trace, as far as we were able, the real 
conditions of growth required by the turnip, and to distinguish 
these firom those of the crops to which it is to a great extent 
subservient. To attain our object it will be necessary to speak 
of amounts of produce which may at first sight excite tie ridicule 



6 AgricuUurdl Chemistry — Turnips, 

of those who do not fully appreciate the nature of the qnestion 
at issue ; but those who choose to go through the details which 
we are about to quote will, it is thought, find that a true under- 
standing of them tends much to explain the principles upon 
which the best agriculture is founded. 

Before entering upon a consideration of the turnip results 
themselves, we shall remind the reader of some of the leading 
facts which may be assumed, regarding the conditions of growth 
of the wheat plant. 

In the paper on " Agricultural Chemistry " in the last number 
of this Journal, a series of experiments was quoted for the pur- 
pose of showing the efiect of season and manwririg upon the 
growth of wheat ; and a careful consideration of them led to 
some very important conclusions regarding the nature of the ex- 
haustion by corn-cropping, and also as to the varying nutritive and 
marketable value of specimens of grain having different characters 
and composition, traceable to known conditions of growth. 

It was seen that the varying quantity and the quality of the 
produce of a plot of land, unmailured during several successive 
seasons, were materially dependent on the number of rainy days, 
the inches of rain and the temperature, of the months of May, 
June, July, and August, during which periods the accumulative 
and elaborative processes of the wheat plant are most actively 
determined. The average annual produce of the soil and season, 
unaided by manure, amounted to about three-fourths of the esti- 
mated yield of the neighbourhood under ordinary cultivation — 
to two-thirds of that of a plot manured by farmyard-dung — and 
to fully half as much as might be expected from as high a course 
of farming as the soil and the climate with which we have to deal 
would justify us in adopting. It is remarkable too that, whilst 
the quality of this natural produce, as indicated by the relation of 
com to straw, and the weight per bushel of the com, varied year 
by year according to season, yet the characters of the crops grown 
by very various and, in some cases, rather high manures, were for 
each season somewhat similar to those of the produce of the 
unmanured plot. It is evident, then, that the conditions favour- 
able to an increased growth of wheat are perfectly consistent in 
Tdiid with the natural tendencies of the plant, and that they only 
differ quantitcUively from the natural resources of soil and season, 
and less indeed in this respect than might have been supposed. 
The following table exhibits the influence of season upon the 
produce of tumip-bulb unaided by the supply of manure. The 
soil upon which the experiments were conducted was a somewhat 
heavy loam, not well suited for turnips : the previous crops since 
manure having been wheat, clover, wheat : — 













Agricultural Clismistry — Turnips, 


7 




Seuon. 


No Manure. 




Bulb per Acre In 


Ayenge weight 

of bnlbs In lbs. 

and tenths. 




1843 


Tons. owts. qrs. Iba. 
4 3 3 2 


0-62 






1844 


2 4 10 


0-36 






1846 


13 2 24 


Oil 





It is seen that in three years the produce of this unmannred 
plot was reduced from 4;^ tons to 13^ cwts. per acre ; in the 
fourth season (1846) the bulbs only averaged the size of a radish, 
and were considered to be not worth weighing. This result 
strikes us as the more remarkable when we reflect that to the 
turnip is attributed a power of reliance upon the atmosphere for 
its organic constituents, to which it is supposed is due its efficacy 
in restoring fertility to the soil, and increasing the after-growth 
of com, which itself attains to a moderate crop under the influence 
of soil and season alone. The evidence here afforded of the 
totally artificial conditions which are induced in the cultivation 
of the turnip for feeding and manaring purposes, is of the clear- 
est kind ; and we shall have occasion further on to refer to other 
points than those here given, as illustrating so carious a result. 

Our present object is to show the entire absence of any bene- 
ficial influence of season upon the growth of the turnip, indepen- 
dently of artificial supply of constituents. An inspection of the 
two following tables, giv&g the results obtained by various 
manures during three seasons, and the characters of the seasons 
themselves, affords some insight into the general influence of cli- 
mate upon the growth of the cultivated turnip. It must be ad- 
mitted, however, that the relation is by no means so quantitatively 
definite as in the case of wheat; whilst the conditions suited to the 
&vourable growth of the two plants are very opposite in kind: — 



1843 
1844 
1845 



Bulb per Acre, in Toaa, cwts., qra., and Iba. 



Sknnyud- 
dnng. 



9 






9 2 9 



10 15 1 
17 3 6 



Superphosphate 
of lime. 



Tom. cwu. in. \h*. 

12 3 2 8 

7 14 3 

12 13 3 12 



Mixed earthy 

and alkaline 

Phosphates and 

Sulphates. 



To*!, cwtib ^if. Ibf. 

11 17 2 
5 13 2 

12 12 2 8 



Average weight of Bulbs 
in lbs. and tenths. 



18 Tons 
Farm- 
yard- 
dung. 



1-36 
119 
1-61 



Snp^- 

phos- 

phate of 

Lime. 



1-47 
0-81 
117 



Mixed 
earthy and 

alkaline 
Phosphates 

and 
Sulphates. 



1-35 
0*68 
116 



& Agricultwral Chemistry — Turnips. 

A detailed consideration of the produce of the several seasons 
under different conditions of manuring, as just given, cannot fail 
to show in which were the climatic influences most favourable to 
the growth of the cultivated turnip. It will be remembered that, 
without manure, the produce of the first of the three seasons was 
much below the most meagre agricultural amount ; and that in 
the third and fourth it dwindled to almost nothing. This table, 
on the other hand, shows that under a course of manuring the 
third season yielded the largest crop, and the second invariably 
the least. The average produce of the first season, where farm- 
yard-dung is employed, is not superior to that of the second 
season under similar conditions of supply, though it is so in each 
of the cases where mineral manures alone are used. If we look 
to the average weight of the bulbs, however, as given in the 
table, it will be seen that the development was superior in the 
first year to that in the second, though inferior to that in the 
third. The seeming depreciation in the first season, indicated 
by the acreage yield, arose from the adventitious circumstance 
of the greater destruction of plants by disease in that season, 
from which cause their number was greatly diminished. The 
discrepancy is, therefore, apparent rather than real ; the result 
being dependent, not upon the a/mount of supply by season and 
manure, but upon injury which is more frequently connected 
with rich than with poor manuring. Again, neither the acreage 
produce nor the average weight of bulbs, where mineral manures 
alone were employed, shows so marked a superiority of the third 
season as compared with the first, a^ is evinced in the case of 
the farmyard-dung, by which a large amount of organic matter 
was supplied to the plants. We shall have occasion to show, 
however, when treating of the effects of manures upon the growth 
of the turnip, that there was a deficiency of carbonaceous supply 
in the soil in the cases where mineral manures alone had been 
used, which gave to the farmyard-dung its superiority in the 
third season. Upon the whole it is evident from the results, 
that of the three seasons the third was by far the best suited to 
the growth of the turnip for feeding purposes, and that the 
second was the least so. 

Of the real character of these seasons some judgment may be 
formed by an inspection of the following table, in which is given 
a summary of the statistics provided by the rain-gauge and the 
register thermometer, in reference to the climate of the three 
seasons during the months of July, August, September, and 
October, which may be considered to include the period of the 
active growth of the turnip : — 



Agriculktral Chemistry — Turnips. 



Daring Jnly (last 14 days). 


During Angnst. 


Season. 


Mean 
Tempera- 
tore. 


No. of 
rainy 
days. 


Inches 

of 
Bain. 


Season. 


Mean 
Tempera- 
ture. 


No. of 
rainy 
days. 


Inches 

of 
Rain. 


1843 
1844 

1846 > 


69-7 
66-8 
69-4 


11 
3 

7 


104 
0-65 
0-97 


1843 

1844 
1846 


63-4 
69-7 
590 


12 
14 
17 


3-38 
1-84 
2-79 



During September. 


Daring October. 


Eeaaon. 


Mean 
Tempera- 
ture. 


No. of 

rainy 

days. 


Inches 

of 
Rain. 

0-98 
1-38 
1-77 


Season. 


Mean 

Tempem- 

tnre. 


No. of 

rainy 

days. 


Inches 

of 
Rain. 


1843 
1844 

1845 


61-9 
68-9 

64-8 


6 

14 
14 


1843 
1844 
1846 


490 
50-2 
600 


15 

17 
10 


2-62 
413 
1-39 



By such a sammaiy as is here given, of course only the gene- 
ral differences in the seasons are brought to light; but our 
readers will probably admit that the greatly increased labour of 
examination, were the table more extended and in detail, would 
scarcely be compensated for, if the main characters, requisites, 
and offices of the turnip season can be ascertained without it. 

A relatively large number of rainy days, an enhanced actual 
amount of rain, and a low degree of temperature, are prominently 
the characters which distinguish the assumed turnip season of 
1845 from that of the two preceding years, and during a con- 
siderable portion of the period, especially, from that of 1843. 

Thus, taking the items somewhat in the order in which they 
are given, we find that in the latter half of the month of July, 
upon the character of which so materially depended the early 
development of the plant, and on this its future growth, in the 
seasons of 1843 and 1845 the temperature was lower than in 
1844 ; and in 1845 the number of rainy days is more than double 
that in 1844, though somewhat less than in 1843, whilst the total 
amount of rain was much greater in 1845 than in 1844, and 
nearly equal to that in 1843. In August we have in 1845 the 
lowest temperature, the greatest number of rainy days, and, 
though not the largest actual amount of rain, a quantity large 
compared with 1844, though below that in 1843. September 
indicates still the lowest temperature in 1845, a number of rainy 
days equal to 1844 and far exceeding 1843, and also the largest 
actual amount of rain. The month of October, on the other 




10 Agrioultural Chemistry — Turnips, 

hand, shows in 1845 the smodlest number of rainy days, as well 
as actaai fall of rain, and a mean temperature not so low as in 
1843. 

In these facts, even though so general and limited in their 
indications, there is scarcely one which does not show that the 
most fisiyourable conditions of growth for our cultivated, bulb- 
forming turnips are, relatively to those for the seed-producing 
gramineous plants, a low degree of temperature, a large number 
of rainy days, and a large actual amount of rain. The seeming 
deviation from this general postulate, which is indicated by the 
character of the month of October in the third or best turnip 
season, is, however, by no means inconsistent with our estimate 
of the requisites of such a season, but rather conduces still further 
to account for the observed superiority of effect ; for whilst, com- 
pared with plants which are cultivated for highly elaborated 
products, such as the cereal grains, we should expect the mainly 
accumulative and deficiently elaborative processes of the bulb 
and leaf forming turnip would require a lower degree of tem- 
perature and a greater amount of moisture favouring the circu- 
latory determinations of the plants, there is, nevertheless, a 
point at which depreciation in temperature is injurious to vege- 
tation. Indeed, the full growth of the turnip crop depends greatly 
on the postponement of the winter temperature, and hence pro- 
bably arose a real advantage &om the relatively high (though 
actually low) temperature in the October of 1845. Again, t^^e 
lower the temperature, the less important are a continuity and 
large amount of rain. 

As a general fact it is evident that the amount of the produce 
of the turnip is very materially dependent upon the climatic 
character of the season, not only as in itself a resource, but as an 
essential agent in the appropriative power of the plant, however 
liberal and complete may be the supply of constituents within 
the soil. Whilst, however, it may frequently happen that the 
physical characters of the season may be such as not to render 
available to the plant, and at once profitable to the farmer, the 
constituents which he has provided by manure, it is evident from 
the results which have been given, that, without an ample 
manuring, the best adapted season is incapable of yielding an 
agricultural amount of turnips. It is to be feared, how^ver, that 
it is more frequently the essential condition of artificial aid, 
rather than that of natural climatic agency and resource, that is 
in defect. 

Common usage seems to attribute to the turnip, and green 
crops generally, a power of collection from the atmosphere which 
is not recognised in our grain-yielding plants; and it may at first 
sight appear inconsistent with this view, that the growth of the 



AgrteuUural Gltemisi/ry — Turnips. 1 1 

tamip in agiicaltnral quantdty should be so essentially dependent 
cm artificial supply as onr results would show to be the case. 
There can be no doubt that there is some truth in this current 
supposition, but there is little doubt that the power of collection 
from the atmosphere very materially depends upon the quantity 
and quality of the supply to the soU by manures ; in fact, that 
upon the mdicious and liberal provision of certain constituents 
bfart we must i«st our hopee for atmoapheric accumulation. 

Having shown, then, that climatic agencies constitute an 
important element in the necessary conditions of growth of our 
cultivated turnip, and that these are only available when asso- 
ciated with an abundant artificial supply of certain constituents, 
the question arises — What are the substances which it is essential 
should thus be provided ? This brings us to the second branch 
of our subject, namely, the influence of manuring upon the 
growth of the turnip. 

Having discussed in some detail the comparative characters of 
the first three seasons during which we have been conducting 
an extensive series of experiments, under very various yet known 
conditions of manuring, we are prepared to consider the results 
of those experiments ; and it is believed that those of them which 
were obtained in the three years referred to will amply suffice to 
indicate the nature of the necessary supply by manure, and also 
to lead to some interesting and important explanations regarding 
the true office of the turnip in a course of agricultural cropping, 
and the sources of its economic value. We would again remind 
our readers that the object of the experiments was not the pro- 
duction of large crops, but to learn, by the efiects of different and 
known conditions of supply, in what respect and to what extent 
the plant was dependent upon the resources which must be kept 
up by the farmer, and how far he may rely upon the natural yield 
of the atmosphere ; for it is the item of source of constituents, as 
well as that of quantity and quality, which should influence our 
selection of plants and manures under a truly rational and 
eo^momic system of agriculture. 

The experiments were commenced in the season of 1843, the 
early part of which, it will be remembered, was greatly superior 
to that of 1844, and equal to that of 1845 in suitableness to the 
growth of the turnip ; but in the middle and latter periods it was 
inferior to either of the two succeeding seasons. The soil was a 
somewhat heavy loam, not well adapted for turnips ; but as the 
plant is cultivated on such land with admitted advantage for rota- 
tion purposes, it was well fitted to answer our special ends. The 
previous crops since manure had been wheat, clover, wheat ; so 
that in an agricultural point of view the soil might be considered 



12 



Agricultural Chemistry — Turnips. 



as somewhat exhausted, and therefore in a favourable condition 
for an inquiry into the influence of supply by manuring. The 
description of seed was Norfolk Whites. The manures and seed 
were drilled together on ridges, there being 25 inches between 
the rows. The plots allotted to each experiment comprised six 
rows, and consisted of about one-third of an acre. The crop was 
calculated from weighed quantities taken from measured portions 
of land, of about one-eighth of an acre for each lot, and extending^ 
across the series in three different places. 



Table showing the results of Expebimbkts apon the Obowtu of Tubnips 

by Makubbs, at Hothamstbd Fabm, Hbbts. 

Mrst Season, 1843. 



§ 


DSHCRIFTION OF MAXrRES. 


Avemge 




Bulb 








Bulb 

___ A 




weight 


Number 


per acre. 


Bulb 




per Acre, 


Quantities expressed iu weight per acre. 


of Bulbs 


of 


com- 
pared 
with 
No. 2 as 
1000. 


per Acre 




II 


4 puuit« 
in a 


K 


Each lot matlc up at the rate of 14 


in lbs. 


plants 


in tons, cwts.. 




1 


bushels per acre, with clay and wood- 
ashes. 


and 

tenths. 


per acre. 


qrs., and lbs. 


squttiv yiuu := 

19,860 in au 

acr& 










1 


Tp»»». rw»i. ^is. 


I!.*. 


Toitt. 


rwti. ^r*. lb*. 


1 


12 tons farmyard-dung 


1-36 


16,671 


2262 


9 9 2 


9 


11 


16 9 


s 


No manure 


U-52 
li)8 
116 


17,940 
17,043 
16,467 


1000 
1967 
1926 


4 3 3 
8 4 8 
8 1 1 


2 
12 
11 


4 

9 

10 


9 9 6 


8 


6i cwts. rape-oake 


6 9 91 


4 


6| owts. rupc-cake^ 2 bushels yeast 


9 1 


5 


8 bushds yeast 


1-21 


20,240 


2622 


10 19 2 


19 


10 


9 17 


6 


2^ cwts. suporpho^pliate of lime, 12 lb& i 
sulphate of ammonia, 4 bushels of yeast f 


1-33 


19,673 


2796 


11 14 


28 


11 


9 8 17 


7 


56 lbs. sulphate of ammouia 


1-03 


14,996 


1653 


6 18 1 


26 


8 


18 5 


8 


H cwts. superphosphate of limc^^SJ cwts. 
mpe-cnke ) 


1-69 


16,096 


2894 


12 2 1 


21 


14 


18 14 


9 


1^ cwt. superphosphate of lime, 6^ cwts. ) 
rape-cake 


1-68 


16,296 


2490 


10 8 8 


6 


13 


2 8 17 


10 


32 cwts. superphosphate of lime, 1 cwt ) 
rape-oake 


1-68 
1-42 


18,019 
17,928 


8042 
2734 


12 14 3 
11 9 


6 
5 


IS 
13 


IS IS 


11 


Refuse matter containing much precipi- 
tated phosphate of lime, rapeK»ke,&c. 


6 1 93 


li 


2| cwts. superphosphate of lime, 2 cwts. 
rape-oake, 2U lbs. sulphate of ammonia 


1-48 


17,112 


2720 


11 7 3 


7 


18 


16 8 • 


18 


1^ cwt. superphosphate of lime, 1 cwt. 


1-42 


16,617 


2531 


10 12 


5 


12 


6 1 28 




rape-cake, 40 lbs. sulphate of ammonia 


A ^m 


AWrVr& 


m.^0 Mm V 




 • 


V m mW 


14 


1 J cwt. supcrphospliate of lime, 3 J cwt«. ) 


1-23 


17,790 


2340 


9 16 8 


86 


10 


12 9 19 




rape-oake, lu lbs. sulphate of ammonia 


A- ^^f 




■F A VF VF 


••» 


*^r 


m.m A -mm^ 


16 


32 cwts. superphosphate of lime, 2} cwts. 


1-76 


16,088 


2841 


11 17 8 


18 


15 


9 9 




rape-cake, 20 lbs. sulphate of ammouia 


1 f V 


M\rm^ 


A A- A ff W 


M\J 


IV 


mm V 


16 


3{ cwts. superphosphate of lime, 1^ cwts. 
phosphate of magnesia-manure 


1-39 


19,975 


2974 


18 9 


16 


IS 


19 


17 


S^cwtA. superphosphate of lime, 160 lbs. ) 
phosphate of potass-manure . . . . " 


1-36 


19,888 


2804 


11 14 8 


19 


11 


16 9 


18 


Zi cwts. superphosphate of lime, 84 lbs. 
phosphate of magnesia, 76 lbs. pYios- 


















1-35 


19,642 


2836 


11 17 2 





11 


13 1 IS 




Dhnte of Dotass 
















19 


w^  ^JV^n^^^ ^^ ■* K^^«^ v^v ■'^^«v 9w VV #v  99 

AjB 18, with 30 lbs. sulphate of ammonia 


1-49 


19,113 


8046 


12 6 


13 


12 


17 9 6 


SO 


3} cwts. superphosphate of lime, 1| cwts. ) 
rape^cake, 16 lbs. sulphate of ammonia j 


1-58 


16,916 


2860 


11 19 1 


88 


13 


18 13 


81 


Unbumt bones decomposed by sulphuric 
acid, 7 bushels 


1-48 


17,676 


2804 


11 14 8 


19 


12 


16 8 • 


29 


44 cwts. superphospluite of lime . . . . 
Clay and weed^slies only, 15 bushels . . 


1-47 


18.446 


8908 


12 3 8 


8 


IS 


14 10 


88 


132 


18,746 


2660 


11 1 3 


81 


11 


8 90 



The tenns miperjihospliate of lime, phosphate of {totiiss, phospliate of soda, and phosphate of magnesia* 
as found in this table, and others whicli follow it, are not to be understood as representing the pore 
chemical substances bearing those names. Hie composts were formed by acting upon calcined bone^nrt 
by means of sulphuric acid in the first instance : and in the case of the alkaline salts, and the magneaiaa 
one, nentralising the compound thus obtained, by means of cheap preparations of the rcqieotlve bases. 



A€^ricuUural Cltemistry — Turnips. 13 

Were we to look at the results of this Table with a purely 
agricultural eye, the column of acreage weight of bulb would be 
sufficient to guide our judgment as to the efficiency of the various 
manures ; but since the object of the experiments is rather to 
provide a key to the requirements of the turnip than to afford exact 
examples of manuring, other items than that of the actual acreage 
lesulte obtained must be taken into consideration in forming an 
estimate respecting the nature of the conditions which cultivation 
should be calculated to supply. Manures, indeed, cannot be re- 
garded only as containing certain constituents convertible into the 
substance of the crops, but also as agents acting beneficially or 
otherwise according to the form or combinations in which they 
are supplied, and their adaptation to soil and season. Thus it is 
known that the casualties and tendencies to disease or prevalence 
of insects often prove more destructive to the young turnip-plant 
under high farming, when the soil abounds in animal and vege- 
table matter, than when it is deficient in such substances ; and 
the number of plants ])er acre may by such causes be so greatly 
reduced as to show a better acreage yield under bad than under 
liberal cultivation. The number of plants per acre must not 
therefore be overlooked in considering the results of the Table. 
The average weight of bulb may also be taken as to some extent 
indicating the relative effects of different conditions of growth. 
Where we have an increased average weight, as well as a large 
number of plants, both agency and supply have been favourable 
to the requirements of the plant ; and although the efficiency of 
either of them is dependent on that of the other, it may as a 
general fact be assumed that a high number of plants indicates 
a favourable condition^ and a large average weight a favourable 
amomU of supply. Bearing in mind these considerations, we have 
given in the last column of the Table the estimated acreage yield, 
calculated from the actual average weight of bulb, and supposing 
a uniform number of plants per acre, namely, 19,860, or 4 in a 
square yard. Such an arrangement would give about 12^ inches 
from plant to plant along the rows, and may be taken as affording 
a more just view of the effects of the manures, independently of 
the contingencies arising from the manner of their applicatiou. 

In reference to the results of this first season it must further be 
remarked, that the previous course having been wheat, clover, 
wheat, the peculiar exhaustion of the soil would be that induced 
by coni'Cropping ; and if there be any truth in the opinions which 
we have given elsewhere on this subject, this would imply a de- 
ficiency of nitrogen relatively to other constituents, so far as the 
future growth of wheat would be concerued ; and it would appear 
from the amounts of produce without manure during the three 
seasons, as already given, that in some important respects the con- 



14 



AgrimUural Ohemistry — Twrmps. 



ditions of exhaustion most favourable to an investigation into the 
effects of supply for the growth of the turnip, were not so promi- 
nent in the first season as afterwards, when tibe unaided yield was 
little more than a weed, so that the entire produce under manures 
could then be attributed either to their agency or their supply. 

The following selected results, showing the average weight of 
bulbs and number of plants per acre, yielded by manures which, 
compared with each other, are respectively mineral, nitrogenous, or 
carbonaceous, will point to some of the conditions which it is essen- 
tial to provide for the healthy and rapid growth of the turnip : — 

Sblkctbd Results. 



Plot 
No*. 



2 
3 

7 

16 
17 
18 { 
22 ' 



{ 



Detoription of Manorei. 



^1 Q UiAUuXv ••• ••■ ••• ••• ••• •«• ••• ••• ••• 

O3 C^WvS* XaX)0*G& KO ••• ••• ••« ••• ••• ••• ••• 

66 lbs. sulphate of ammonia 

3} cwts. saperphosph. lime, 1^ cwt. phos. of magn. 1 

* manure j 

150 lbs. phos. potass manure 
84 lbs. phos. mag. 75 lbs. 1 



Number 

of 

Plants 

per Aere. 



ft 



» 



» 



It 

ft 



4^ cwts. 



phos. pot. manure 



»t 



I* 



17,$*40 
17,043 
14,996 

19,976 

19,228 

19,642 

18,446 



ATemgv 
Weight of 

Bulbs 

In Uml and 

tentha. 



0-52 
108 
1-03 

1-39 

1-36 

1-36 

1-47 



The figures in the first column show a great destruction of 
plants under direct ammoniacal supply, as well as considerable 
depreciation where rape-cake was used ; and common experience 
teaches us that, however useful rape-cake and ammoniacal salts, 
or guanos containing much ammonia, may be as manures for 
turnips, substances of their description are never safely applied 
near to the seed. Other instances than those quoted above from 
the table at page 12 distinctly show the injurious influence of 
organic manures when drilled with the seed ; indeed, it may be 
laid down as a general rule that, especially for all spring crops, 
it is much more safe to apply such matters broadcast, and incor- 
porate them well with the soil. The conflicting accounts which 
are given of the effects of guano and ammoniacal salts when they 
are supplied to spring com crops, and of these manures and 
rape-cake when used for turnips, are, it is believed, mainly attri- 
butable to differences in the manner of their application ; and 
whilst with a very wet season no injury, or perhaps benefit, may 
arise from the use of the manure drill in such cases, by far the 
safest course is to sow broadcast. 

The second column of the selected results shows for this season 
of 1813 a considerable superiority in point of developmerUy as well 
as numl)er, of surviving plants, under purely mineral by the side 
of organic manures ; and, compared with the unmanured plot, 



AgricuUvral Chemistry — Turnips. 



15 



tliOBe having mannree only mineral indicate a growth almost 
threefold in the same space of time, whilst the actual acreage 
amount of produce is in these cases very nearly as great as in 
any of the series ; indeed, mineral manures alone have nearly 
trebled the unaided produce of the soil and season. 

These results might almost lead us to question the importance 
of organic manuring for the turnip crop, and to assume that a 
deficiency in mineral matters was the source of impoverishment 
in the case of the soil selected for experiment ; but as we proceed 
it will be seen that, however marked mav have been the effect of 
mineral matters in developing the powera of growth of the plant, 
as long as a sufficiency of organic food remained, yet a point of 
exhaustion was arrived at when, by a less amount of mineral 
matter, if in conjunction with organic supply (especially such as 
could yield carbon to the plants), the rapidity of bvJb formation 
was materially enhanced. 

Before leaving these results it is as well to observe, that not- 
withstanding the large amount of potass required by the turnip, 
the direct supply of that alkali did not give a produce superior 
to that by superphosphate of lime. We shall have occasion to 
recur to tiie question, whether part of the effect of the latter 
manure is not due to its liberation in the soil of alkalies not 
otherwise available to the plant. All we wish to call attention 
to at the present is, that' there was an abundant amount of alkalies 
in this corn-exhausted soil, which could be rendered serviceable 
under suitable management. 

The next quotations which we shall make from the table (page 
12) will serve to illustrate the effect of the artificial supply of 
matter for organic formations, aided by certain mineral agency 
and constituency : — 

SBLBCTBD RBSmiTS. 



Pbt 
Hoc 



8 

9 

10 

14 
15 

"1 

20| 



DescripUoii of Manures. 



weight 
ofBnlbs. 



Average Number 



2| cwts. superphosphate of lime, 3} cwts. rape-cake 

^4 M ft fi^ „ „ 

5« 1 

2\ cwts. superphosphate of lime, 2 cwts. rape-cake, 1 

20 lbs. sulphate of ammonia ) 

1} cwt. superphosphate of lime, 1 cwt. rape- cake, 

40 lbs. sulphate of ammonia 

H cwt. superphosphate of lime, 3} cwts. rape-cake, 

10 lbs. sulphate of ammonia 

3f cwts. superphosphate of lime, 2} cwts. rape-cake, 

20 lbs. sulphate of ammonia 

3| cwts. superphosphate of lime, 84 lbs. phosphate 

magnesia, 75 lbs. phosphate of potass, 30 lbs. sul 

phate of ammonia 

3^ cwts. superphosphate of lime, 1^ cwt. rape-cake, \ 

16 lbs. sulphate of ammonia / 



   I 

:e, \ 



of Plants 
per Acre. 



i6,a9<; 

16,295 
18,009 




16 Agricultural Ohemistry — Turnips, 

It may be objected that the average weight of bulbs, as stated 
above, is in itself small, and that the differences exhibited are too 
slight to be relied upon as showing a result. We would beg to 
say, however, that the estimations were taken from the whole of 
the bulbs that were weighed in each case, amounting to nearly 
2000, and that we believe they may be depended upon for our 
present purpose. 

It will be remembered that with mineral manures alone there 
were, on an average, rather more than 19,000 plants per acre, 
but a glance at the results just given will show how uniformly the 
direct supply by the drill of " organic manures " tended to lessen 
the number. Again, it has been seen that the highest average 
weight of bulbs (indicating the degree of development) was, by 
purely mineral manures 1*47 lb., by sulphate of ammonia 1*03, 
and by rape-cake alone 1*08 lb. The fact that these conditions 
of manuring, employed singly, fall far short of their effects when 
combined, help us to form some judgment as to the point at 
which the one or another class of constituents seems to fail, 
either in quantity or in adaptation to the wants of the plant. 

Taking the lots 8, 9, and 10, we find the largest number of 
plants where the proportion of mineral supply to that of rape- 
cake is the greatest, and the smallest number where the rape-cake 
is relatively in excess. The weight of bulbs is least where the 
mineral matters are most in defect, and greatest where neither 
condition was to the other so prominent as in the other two cases. 
Again, taking Nos. 12, 13, 14, and 16, in which superphos- 
phate of lime was united with both rape-cake and ammoniacal 
salt, the largest weight of bulb in the entire series of the season 
is found to be in that case where, with a fair supply of each, no 
one of the several manures predominated so much as in either of 
the three other instances just mentioned. 

Were we to place unconditional reliance upon mere supply of 
constituents for actual conversion into the substance of the plants 
we should expect that the farmyard-dung would give, in every 
respect, the best crop in the series ; but agency, as distinguished 
from mere supply, seems to constitute a most important item, 
affecting the development of those truly artificial conditions of 
growth which the cultivation of the turnip, for feeding and 
manuring purposes, so pre-eminently implies. In the farmyard- 
dung we had undoubtedly the largest provision of nitrogenous, 
and especially of carbonaceous matter, and it may be supposed 
that it also brought to the soil such an abundance of all the 
mineral substances as would be contained in a much larger crop 
than was produced by it. 

The results arranged below will sufficiently prove that, how- 
ever liberal the supply of all required constituents, the health 



Agricultural Chemistry — Titm-iji^s. 



17 



and vigour of the plant, or its power of appropriating the food 
presented to it, de{>enda upon other circamstances than the mere 
amctmi of that food. 

SeLBGTSD RKSULT3. 



Plot 
Koi. 


Description of Manures. 


Average 

Weight of 

Bulb. 


Number of 

Plants 

p^Acre. 


1 

8 

15 

18 

22 


12 tons farm-yard duog 

21 cwtu. superphosphate of lime, 3} cwts. rape-cake 
3f cwts. superphosphate of lime, 2} cwts. rape- ' 

cake, 20 lbs. sulphate of ammonia 

3J cwts. superphosphate of lime, 84 lbs. phosphate 1 

of magnesia, 75 lbs. phosphate of potass 

4^ cwts. superphosphate of lime 


1-36 
1-69 

1-76 

1-35 
1-47 


15,571 
16,096 

15,088 

19,642 
18,446 



We see that the farm-yard dung gave a number of surviving 
plants nearly as small as any in this series, and very far short of 
that obtained by mere mineral, or frequently by mixed mineral 
and organic supply. Again, the weight of bulbs is only equal to 
the lowest resulting from pure mineral manuring, and inferior to 
that in other cases of such manuring. In Nos. 8 and 15, on the 
one hand, the amount of supply, especially of matter for organic 
formations, was much less than in No. 1 , whilst the average weight 
of bnlb was materially greater. On the other hand, the mineral 
supply was in these cases less than in 22 ; but there being in that 
instance no provision by manure of organic matter, the increased 
mineral supply was unavailing. 

Clay and weed-ashes alone, as in No. 28, are seen to more 
than double the unaided produce of the soil and season, to give 
a fiur number of plants, and an average weight of bulb nearly 
three-fourths as great as in any case in the series. This is a 
curious result, and indicates that certain mechanical as well as 
chemical conditions of soil, in immediate proximity to the young 
plant, are essential to a favourable and healthy development of its 
organs of collection. We learn, too, that in some ' important 
respects the resource of food within the soil itself could not have 
been so low in this first year as it appears afterwards to have been. 

There are other points indicated by the results already given, 
than those to which we have directed attention ; but as a con- 
sideration of the experiments of the succeeding years will bring 
them before our readers, we need not enter upon them in this place. 

Having examined in detail the results of the first year's experi- 
ments, it may be well to reiterate some of the more general and 
important facts and conclusions which have been elicited. It is 
clearly shown that, under the influence of the same season, and 
in a soil which, by corn-cropping, had been brought to that con- 
dition of exhaustion which common usage would remedy by the 

C 



18 AyrwuUural Chemistry — Turnips. 

growth of turnips or other green crops by means of manure, the 
attempt to grow such rastoraUve crop without supplied aid, — ^that 
is, manure, — is quite unavailing. We see that agency as well as 
supply is an essential element to be considered in the choice of 
manures, and that unless such agency or condition of healthy 
function be secured, a liberal provision of the materials of which 
the plant is built up may frequently, to a great extent, be useless 
to it. The matters which are most favourable to the healthy 
action and rapid accumulation and assimilation by the turnip, 
are the so called ^^ mineral manures,'* under the influence of 
which a great regularity of plant and vigorous power of growth 
are attained. At any rate, in the soil in question, when in a 
condition of agriculturai exhaustioTiy the supply of potass by direct 
manures seems unessential. But the direct supply of phosphoric 
acid, whether by its reaction upon the soil or a special effect 
upon the young plant, or from a combination of these inflaences, 
seems to enhance the assimilating actions of the turnip to a 
degree much beyond what could be attributed to it as a mere 
constituent^ rather than in some sort an agewt also. We shall 
recur further on to this interesting subject. 

Of the substances which we may term pure constituents^ " or- 
ganic matters" and especially such as abound in carrhon, must be 
supplied for the production of agricultural crops of turnip-bulbs. 
These manures, as well as those which are chiefly nitrogenous, 
should never be concentrated near to the plant in its earliest 
stages of growth, but only within its reach, when, under the 
immediate influence of mineral manures, the young plant has so 
far developed its organs of accumulation, and its healthy vigour, 
as to be competent to grow faster than the natural atmospheric 
and soil resources of nitrogen and carbon enable it to do. These 
are, we conceive, the most prominent indications afforded by the 
lesults of this our first season of experimenting upon the culti- 
vation of the turnip. As we proceed in our inquiry we shall 
see how far they are confirmed by those which succeeded them, 
and which we shall now endeavour to detail. 

The whole produce, leaf and bulb, of 1843, was carted off the 
land. In the second year the manures had some reference to the 
condition of soil as affected by the first year's treatment, and the 
same division of the land, and numbering of the plots, were 
adopted. The manures were again drilled with the seed, and the 
mechanical culture of the land before and afler sowing, the estima- 
tion of the crop, and its entire removal, were conducted as before. 

The entire series of results of this second season (1844) are given 
in the following Table at one view, but we shall make selections 
as before, for the convenience of detailed examination. 



AgricuUurcd Chemistry — Turnips. 



19 



Tabu showing the resnllB of Bxpkriicbnts on the Gbowth of Tubnips by 

HAHUBBB at BOTHAMSTXD FABM, HBBTS. 

Second Beaton, 1844. 



I 

B 

9 





s 



Dhcbiptiom op Maxurss. 

Qiastifcies cxpreMed in weight per acre. 
Each lot made np at the rate of 14 
boiheU per acre, with clay aud weed- 



Average 
weight 

of Bulbs 

inlbe. 

and 

tmths. 



1 

Si 

S 

4 

I 

I 

T 
I 

f 

10 
U 

u 

IS 
14 

li 
IC 
17 
IB 

II 



» 



IS tons farm- jard dxmg 

Unmanttred 

7 cwta. rape-oake 

4 ewt&. saperplKMphate of lime, | cwt. 
phoaphate of ammonia 

4evtfl. niperphosphate of Iime,| cwt. 
nlphate of ammonia 

5 ewts. raperphoaphate of ltme» 15 lbs. 
phosphate ol ammonia 

S cwta gnrand apatite 

3 cwta. mixtore of apatite and sol- 
pfaaiicacid,oontaining 200 lbs. apatite 

As Na 8, with 66 lbs. hydrochloric acid 
added (sp. gr. USA) 

4 cwta aaperplMMphate of lime, 4 cwis. 
npe-cake 

4 cwta. saperpluMiphate of lime, 4 cwta. 
npeNcake, 16 Iba. phosphate of am- 
mnnia 

i evt&. saperphosphate of Ume^ land dug 
I inchefi deni 

4 ewtc sapcrpboaphate of lime, 4 cwta. 
npecake, 2 cwts. common aalt 

i cwta. anperphosphate of lime, land 
trenched with the spaile 18 in. deep 

1 cwt. saperphoephate of lime, 4 cwts. 
phosphate of soda 

1 evt. soperphoephate of lime, 4 cwts. 
phosphate of magnesia 

1 cwt. saperpbosphatc of lime, 4 cwts. 
phosphate of potaas 

5 cwta. saperpliosphate of lime, 1 cwt. 
each of phosphate of potass, soda, and 
magnesia 

Sameas No. 18, with 16 lbs. phosphate of 
ammonia 

S cwta, anperphosphate of lime, 4 cwts. 
iape«ake, 66 1 ba. sulphate of ammonia 

174 Iba. mlxtnre of apatite decomiioscd 
byralphnrio acid, eontaininfr 104 Ibv. 
Sulphuric acid, 27u lbs. apatite. . . . 

S cwtSw snperphospliAte of lime . . . . 

S ewts. superphosphate of lime, 56 Wa, \ 
wlphateof ammonia, 1) cwts. nitmte r 
ofsoda ) 



1-19 
0*36 
Q-Vt 



1*29 

0-97 
0-90 
0-99 
0-76 
0-70 
0H)6 

0*68 

0*78 
0-78 

0-86 
0-81 
0-83 



Number 

of 

plants 

per acre. 



30,096 

13,736 

6,488 



0^2 


16,768 


0-87 


14,266 


0-66 


21,632 


0-88 


17,864 


0-71 


21,232 


0-80 


20,892 


1-18 


13,266 



10,820 

20,162 
7,962 
13,360 
19,504 
21,336 
20,562 

18,624 

20,352 
6,832 

18,728 
21,305 
10,072 



Bulb 
per acre, 
com- 
pared 
with 
No. 2 as 
1000. 



4875 

1000 

294 

8188 

2498 

2867 
1382 
8076 

8820 

8178 

2697 

8968 
482 
2683 
3018 
3024 
2775 

3572 

3107 
1084 

8247 

8503 
1700 



Bulb 

per Acre 

in tons, cwts., 

qrs., (vnd Iba 



10 15 1 




2 4 

13 



7 
7 



1 




6 8 2 



6 6 2 
3 1 
6 15 8 



6 2 





8 16 1 

111 

5 18 1 

6 13 
6 13 2 
6 2 2 








6 10 1 












5 19 












5 18 2 

6 13 1 

2 7 8 

7 8 10 

7 14 8 

3 15 



Bulb 

per Acre, 

if 4 plants 

ina 

square yard a 

19,860 in an 

acre. 



Tout. rw*. T* lfc«. 

10 15 2 22 



8 
2 



2 
6 




2 



26 
9 



7 19 8 

7 10 1 16 

6 12 1 12 

3 5 2 20 

6 2 2 26 

6 18 1 4 

10 8 3 24 

11 2 3 26 

8 7 2 19 
2 11 3 12 
8 11 14 
6 11 1 13 
6 10 
5 14 9 

5 17 2 4 

6 6 20 

6 14 3 8 

7 6 3 30 
7 1 
7 1 3 SO 



On reference to the summary as already given of the climatic 
conditions of the turnip seasons of 1843 and 1844, it will be seen, 
that in the latter half of the month of July, the low degree of 
tempemture, the number of rainy days, and the actual amount of 
rain, are all most favourable to the early stages of the plant in 
1843. Throughout the months of August, September, and Octo- 
ber, on the other hand, the conditions of turnip growth, so far as 
season is concerned, are more favourable in 184i than in 1843. 

c 2 



20 



Agricultural Ghemishy — Turnips, 



A glance at the mean results of the two years will, however, 
clearly show that if the climatic influences of the second year were 
in the main superior to those of the first, some other circumstances 
must be looked for, as accounting for the great falling off in the 
development of the plant. 



SBLBCTED and MBA.N BBSULTS. 



Description of Manures. 



• » • • • • 



No manure 

Mean of mineral supply 

Rape-cake only .. 

Mean of mixed mineral and organic supply 



••• ••• 



••• ••• ■•■ 



Average Weight 
of Bulbs. 



1848. 



0-52 
1-39 
108 
1-60 



1844. 



0-36 
0-73 
027 
0-97 



Number of Plants 
per Acre. 



1843. 



17,940 
19,323 
17,043 
17,230 



1844. 



13,736 

20,377 

5,488 

14,774 



It is here seen, that with a more favourable season, excepting 
during the first few weeks, in 1844 than in 1843, we have never- 
theless an inferiority of development under every variety of 
manuring, and a very marked depreciation in the number of 
plants, unless where mineral manures alone were used. The 
destructive efiects of organic manures, especially in the absence of 
rain during the early stages of growth, are here very evident ; and 
the maintenance of healthy action, even under these same climatic 
circumstances, when purely mineral manures are employed, is 
clearly shown. We observe, too, that whilst under the influence 
of this defect of rain during the first period of the season, both 
the weight of bulbs and number of plants are much less where 
rape-cake is used alone than even where no manure at all is pro- 
vided, yet the admixture of mineral manures with the organic 
gives the best result in the series so far as development is con- 
cerned. 

That the cause of the depreciation in average weight of bulbs 
during this season was, nevertheless, connected with a deficiency 
of matter for organic formations, and not of mineral supply, the 
following extracted results will show : — 



Agricultural OhemisU^ — Turnips. 



21 



SiSLSOTBD RBSULTS. 




15 
16 
17 

18 

19 
22 
5 
10 
11 



1 cwt. superphosphate lime, 4 cwt. phosphate soda mannre 
1 ,, ,, 4 ,, phosphate magnesia manure 

1 1 1 f 9 ^ f I phosphate potass manure 

2 ,, ,, 1 fj each, phosphate potass, soda, 
and magnesia, manure 

As 18, with 16 Ihs. phosphate ammonia 

5 cwts. superphosphate lime 

4 , , , , i cwt. sulphate ammonia 

4 ,, ,, ^ t) rape>cake 

4 , , , , 4 , , , , 16 lbs. phos 



amm 



Average 
Weight of 
Bulb in IbB. 
and t42ntha. 



} 



0-76 
0-70 
0-66 

0-68 

0-73 
0-81 
0-87 
118 
1-29 



Thus, of the pnrely mineral manures, the superphosphate of Ume 
(No. 22), as in the first year, gives a higher weight of bulb than 
any of those where alkalies are also supplied. The substitution 
of 1 cwt. of superphosphate of lime, by half a cwt. of sulphate of 
ammonia (see Nos. 22 and 5), raises the weight of bulb from 
0-81 to 0*87 ; by 4 cwts. of rape-cake (No. 10) to 1-18 ; and by 
4 cwts. of rape-cake, with 15 lbs. of phosphate of ammonia, to 1*29, 
the highest weight obtained during this season — that by dung not 
excepted. 

The farm-yard dung, as in the previous year, must be supposed 
to have afforded the most liberal supply of all the matters 
necessary for conversion into the substance of the plant ; yet we 
find that 4 cwts. of superphosphate of lime, with 4 cwts. of rape- 
cake, and 15 lbs. of phosphate of ammonia (No. 11), give a 
higher average weight of bulb than the farm-yard dung ; that by 
the former being 1*29, and by the latter 1-19. We have, how- 
ever, 20,096 plants per acre by farm-yard dung, and only 10,320 
by the artificial organic compost. This deficiency of plants is, 
however, easily accounted for, by the fact that the dung was 
ridged in, and the artificial compost driMedmth the seed ; so that 
the defect of rain during the early stages of the plant, whilst it 
might only retard growth in the one case, would lead to positive 
destruction in the other. 

The very great destruction of plants, as well as the small 
weight of bulb, in the case of No. 8, where rape-cake alone was 
drilled with the seed, further show the impropriety of applying 
organic manures near to the seed or young plant, and the ineffi- 
ciency of mere supply of constituents if the healthy development 
of the collective apparatus of the plant be not secured. The 



24 Agricultural Chemistry — Turnip. 

resource of matter for organic formations were secured ; so that 
the number of experiments was raised to nearly 90. 

It is to be regretted that, in the first two seasons of our experi- 
ments, the acreage produce of leaf, and the relation of leaf to 
bulb, were not taken ; as climate and manuring have a marked 
influence on the character of the turnip-crop in this respect, 
besides that which is known to depend upon the mechanical 
qualities of soil. A consideration of the relative and actual 
amount of leaf is, moreover, found to be of material importance 
in estimating the feeding value, degree of maturity, and probable 
resources of further growth of the plant. All the statement 
which we are able to give on this subject in reference to these 
two years is, that both the acreage weight of leaf, and the propor- 
tion of leaf to bulb, were much greater in 1843 than in 1844; 
there being in the former case a much more liberal provision 
of organic matter remaining in the soil, though, at the same 
time, a less amount of rain and a higher temperature. The 
leaves were weighed in the third year, and so far as the effects 
of different conditions of manuring, under the influence of one 
and the same season, are concerned, the results obtained are of 
some interest. 

The results of the third year (1845) are given in five sections 
or divisions (pp. 26-30), and, for the convenience of reference 
and examination, the statement of the manures is attached to 
each of these divisions. The different degrees of maturity 
exhibited under the influence of the varying supply for organic 
formations, provided by the cross-dressings, led us to weigh some 
of the crops at twice, that their progressive changes might be 
ascertained. The order of maturity which was observed was as 
follows : — 

1st. The lengths under drilled manures only (chiefly mineral). 

2nd. Those having rape-cake added. 

3rd. Those having ammoniacal salt added. 

4th. Those with both rape-cake and ammoniacal salt in addi- 
tion to the mineral manures. 

The first weighing was taken in December, when the leaves 
under mineral supply had considerably drooped and changed 
colour ; the rest exhibiting degrees of retained vitality in the 
inverse order indicated above. The second weighing was taken 
early in January, and three weeks later than the first, as will be 
seen on inspection of the tables. 



AgrieuUva-al Chemistry — Twmips. 



25 



7SyanlB« 
CTOfiMd with 



72y»nl8, 






croised with 


78 yards, 




Bape-cake 


crosaed with 


110 yards, 


and 


Amxnoniacal 


minerals only 


Ammoniaoal 


Salt. 




Salt. 







^ 










09 










« 










^ 










e 










<o 




I 

1 




t» 










CO 










a 










o 






























CO 










^4 
















































V4 








o 








04 










s; 











01 








^ 
^ 






1 



04 

CO 

"*< 

IO 

CD 

00 

o 

rH 

^^ 
•-^ 

09 

CO 

rH 

IO 

•-H 

CO 

rH 

^^ 
00 



O 
04 



04 

01 

CO 
01 



04 



The plan of the field given above will further show the method of mannring 
adq)ted in 1845. In the two previous years each experiment extended from one 
end of the field to the other ; in 1845, bands each of 72 yards down the field, were 
■own, by band, across the rows, respectively, with rape-cake equal to 10 cwts. per 
acre ; 10 cwts. rape-cake and 3 cwts. sulphate of ammonia ; and 3 cwts. of sul- 
phate of ammonia : the manures given as drilled manures being then drilled 
down the entire length of the field. Thus, from 3 to 24 inclusive, each plot of 
knd fonning one experiment in 1843 and 1844 wdA, in 1845, divided into 4. The 
figures represent the same spaces of la^d each year. For example, No. 2 was 
onmaDiired in 1843 and 1844 ; in 1845 one part was unmanured, one was crossed 
with rape-cake, one with rape-cake and ammoniacal salt, and one with ammoniacal 
■Bit. The plan adopted in 1845 has been continued in 1846 and 1847. 



J 



AyrieuUwral Chemistry — Tumipt. 



- 1^ 

A2j 



' a aaa - "s - s s - 






°a a s " "s*- 









aas* s ass s - 



Sails 



lit 



J">SS 8 2SSS S ' 



:! 
a 



-.Jl 



■I '"la 






fKllliir! 



iFii 




xes. =2 aascsa 




S^ZZ ZSS :;= SSSKSS 



26 



AyricuUurcd Chemistry — Twmips. 







ill 



S iOOO 



• 

e» QOOOOOO t« rHMM iH M^ M i^ M ^ M M aO 



1 



i 

4 
m 



» ^ OeOM« viN M<D^ 



O OO ^ « <D O^O^ 
O i-tfH MOM OMOM 

^ ooM »« M fH coe»^o 



it« ». t^«0t«O »- MiHrH e» MvH r4 •-• M tt M M M 



9 
I 



O 



I 

pq 

«H 

o 
H 

I 



O 



i 



«• 

•a 

«| 

CO B 
5 o 

■83 



o 3 - 



I 



js 



2 ooo 



t=s 



OM 
00 






<D QM^O 00 OOOOO O OO WOO '^ O O ^ 

fH Mr4 f-l M 

O fHMiHO M MMO O OO O O O «-400M 

»- I^MOO^ M ^00^ «D OO e» O M « 00 M M 

M OO«0^O 00 MMM M ^M M M M O M M fH 



ttt 

ti 

el 

O 



i2358 *=* ;2;s8*=> s ass 8 ** a 3 a asss'* 



W«»Or-l 

i^o^ 



O ^Mr-lO fH MOO r4 iH M M iH M MMfHMiH 

M t»MiOM 1^ e»ttfH e» 0000 <« ^ M OODMd'^ 

•^ »-t»H fH fH fH (H fH fH 

t« <D<0^e» 00 MMM M MM MMM O M iH iH M 

iHiH^^ fH ^4 iH IH iH IH IH ^4 |H iH 



ll^ 



!• 



«!ai|i 



•• OM 






00 



00 OO-^lOM « ^'«'<« 00 OM ^ O ^ OOOOO 

•H »H rH M M M 

M MrHOce fH ^p-trx M OM MOM M O *H M 

0% OOOrHCO CO ODOlO fH O^OO 00 A 00 lOCDCOO * 



|S 



t<-M M OkMO^ 00 M^^ M ^M '^ M M rH 



li. 



a 
o 



4 to -^ to o ao«'<t««0 o ceooD ^ om o «d oo ooo^m 

i MiH M iHiHMiH M r-i iH Mf 

^M MOiHiHOMOfHMOMOOMOOMOMMM O 

rOMCD r<* <D0M^ M OOtHQO O ^ lO |H M M t^t^MM * t« 

5 tH pH iH ^^ r« iH p^ — IH |H iH tH r^ rH 

|t«0'^ 00 MViOO M MMM ^ ^ rH MOM M^MM •>» 

|2iH fH r^ rH rH iH 1-^ iH iH iH rH t>^ fH fH iH ^H 



I 

a 



•8 



o 
c 







•S CO 

r 

. S 3 o -g 



o 




» "a i^* a. S ^.c '5 oj o o a-a 



lOlHO© 



S8i«: 



;§:: 



'uaqoiQji )om 



fHMM^ »OtO*-COa» Oi-^MM •« Kd CO t^ 00 A O *H M <0 ^ 

rHfHfHiM r-if^fH f»iiH mMmmMM 




AgriouUvral Chemistry — Thtmips, 



Mil 

■S2 



mi 

Mill 



' 88S =■ sa a a a *saa 



: s°* 3 "■- ■» a s 2=8"" 



S* S aS'S 2 23" 



' as s a - ss=" 




ss ssasss 




I :|| I im I s5s s S s 5 5 S !S55 : 



i-Uimtimi S = s 5 1KB-- 



i-niisnUiii S s s s »!Ss5. 



ijfj s gll? I SsS 5 ! 3 S s = gsS5s 



J :|s? 511! 5 555 2 5 5 J g Hm^ 



11* 



<:?l I III! I ssS ! ? 3 s S s SSSs ^ S 



ll 



iiii limn 



i 









4 
III 

t 


Illlilllillllllllllll^^l 


1 


« 


^i||5|lillS5-illlllHII- S 


'! 


lllllllllilllllllllili^ 1 






32 Agricultural Ghemistry — Turnips, 

season, and a number of plants nearly identical with that under 
mineral manures only. Again, by mineral supply alone, to which, 
indeed, as we have seen, may be attributed an influence upon the 
growth of the plant apart from that which can be traceable to 
the mere provision o{ crop-material, we have as many tons of 
produce as the unmanured plot gives cwts., a weight of bulb more 
than ten times as great, and a number of healthy plants nearly 
double. By the side of the farm-yard dung, however, which we 
presume to contain a sufficiency of ail the constituents of a large 
crop of turnips (though, excepting under the influence of con- 
tinuity of rain and a relatively low temperature, not calculated to 
develop the most healthy conditions of growth), we find that the 
purely mineral manuring, with a number of plants per acre 
almost identical, shows a formation of bulb within an equal 
period of time little more than two-thirds as great. We shall 
presently see that the largest weight of hvlh foTToed in a given, 
time is not to be taken as aflbrding an unconditional index to the 
value or promise of the crop ; but in the instances now cited it 
may, in a pre-eminent degree, be quoted as such ; for we know 
that whilst the plants under minerals only had, when weighed, 
arrived at their full growth, those having farm-yard dung had 
still vitality and resources for further development. 

Before tracing any further the probable source of the superi- 
ority of farm-yard over the purely mineral manure, we will refer 
to some other of the points which oar arrangement of manuring 
elucidates. In the two former years it was observed that, 
wherever either ammoniacal salts or rape-cake were drilled with 
the seed, a great depreciation and irregularity in the number of 
plants per acre resulted ; and it may have appeared to some of 
our readers that we have, without sufficient ground, referred the 
deficiency of plants to the manner of applying these organic 
manures ; and that, omitting the indications of the actual acreage 
results, our reasonings are fallacious. The following summary of 
the number of plants obtained, when ammoniacal salts and rape- 
cake are sown broadcast and ploughed in, and of that resulting 
from the use of mineral manures alone, will show how highly 
important it is not only to select a manure such as the plant 
requires, but so to apply it as to ensure a beneficial rather than 
an injurious result. 

The uniformity under the various classes of manures in this 
season, as compared with others, is very striking ; though, as before, 
the mineral manures give somewhat the higher number. The 
coincidence throughout the entire series of about 90 different com- 
binations of manures (see Division 4 of Table, p. 29) is such that, 
for the first time, the acreage amount of produce may be taken as 
a somewhat true measure of the value of the manures. The drilled 



Agricultural Chemistry — Turnips, 



33 



manures, as has already been stated, were this year sown alone 
before the seed, yet the detailed results given in Division 4 of the 
Table still afford instances of the injurious effect arising from the 
proximity to the plant of certain manures, though in so slight a 
d^ree as to be almost immaterial. 



SUMMABY.* 



Deeoription of Manures. 



Mean of mineTal manures alone 

with rape-cake added 

with ammoniacal salt added 

with both rape-cake and ammoniacal salt 



ft 



n 



It 



M 



It 



i> 



Nomber 
of Plants 
per Acre. 



23,882 
22,596 
23,598 
22,954 



The influence of climatic condition, not only as of itself a source 
of constituents, but as rendering available the supplies provided 
by the farmer, is strikingly illustrated by the details next qooted, 
wherein it is seen that notwithstanding the comparatively large 
number of plants in 1845, which might be supposed to prevent 
individual development, there is a marked increase as compared 
with 1844. 



Description of Manures. 


Nmnber of Plants 
per Acre. 


Averoge Weight 
of Bulbs. 




1844. 


1846. 


1844. 


1845. 


Farm-yard dnng 

Mean of purely mineral manures 


20,096 
20,377 


23,731 
23,882 


119 
0-73 


1-61 
116 



It is here seen that, even with so great a number of plants, the 
average weight of bulb is very considerably higher in 1845 than 
in 1844. In the case of the dung the supply by manure is not 
supposed to be better than in 1844. In the case of the mineral 
manores, however, the quantities were larger than before ; but 
the accumulation of organic constituents must have been almost 
entirely from atmospheric resources. A comparison of the 
results of the one year with those of the other, as given above, 
Bufficiemtly prove then the essential influence of climatic agency 
for the development of the turnip-bulb in full agricultural 
qtumtity ; but the great defect in formation of bulb within a given 
time, under the influence of one and the same season, when a full 

* It will be remembered that in former years the plants were set out with the 
Tiewof retaining about four to a square jacd, or 19,360 upon an acre ; the design 
in this third year was to increase the number to about five instead of four, which 
its equal to 24,200 to the acre, and hence the actual numbers in the table just 
given are much higher than hitherto. 



84 



Agricultural Chemistry — Turnips. 



supply of mineral manure only is provided, as compared with 
that of organic matter, also again teaches how imperative it is 
that there be a liberal provision of such matter in the soil, if we 
would produce the largest crop which the characters of the 
season admit of. 

The results already selected from the table do not, however, 
show us whether this required supply by manure of matter for 
organic formations should be more prominently nitrogenous, as in 
the case of wheat, or carbonaceous. This point we shall presently 
recur to ; but, before doing so, shall study the effects of varying 
the mineral supply by manure. 

The average weight of bulb, as affected by the amount of free 
phosphoric acid, or superphosphate of lime, supplied to the soil 
by manures, is here given : — 







Average Weight of Bulbs, in Iboi 










DiiUed 


Plot 
Noa 


Descnption of Drilled Manarca 


Drilled 


DrlUed 
Manures, 


Drilled 
Manures, 


Mannrea, 
aud lOcwta. 






Manures 


and 10c wts.: andSowta. 


Rape-cake. 






only. 


iiape-oake 


Sulph. Am. 


uudScwts. 








per Acre. 


per Acre. 


Sulph. Am. 






0-92 






per Acre. 


8 


400 lbs. calcined bone-dust 


110 


0-96 


0-97 


9 


400 lbs. calcined bone-dust, and ] 












hydrochloric acid = 268 lbs. 


1-02 


116 


0-99 


0-87 




sulphuric acid 










10 


400 lbs. calcined bone-dust, and 
134 lbs. sulphuric acid 


1-18 


1-33 


1-25 


110 


11 


400 lbs. calcined bone-dust, and 
268 lbs. sulphuric acid 


1-23 


1-38 


119 


111 


21 


400 lbs. calcined bone-dust, and 
400 lbs. sulphuric add 

Mean of the results by sulphuric acid 


1-22 


1-41 
1-37 


110 


1-18 




1-21 


118 


lis 



It is seen that, under all the varying conditions of organic 
supply, the undecomposed bone-dust produced less effect than 
the decomposed. Hydrochloric acid has caused a flight increase 
in bulb where there was no organic manure, and where rape-cake 
or ammoniacal salt only was added ; but where ammoniacal salt 
and rape-cake were employed together, the formation of bulb was 
less than by undecomposed bone-dust. But a reference to Divi- 
sion 2 of the Table of collected results will show, however, a 
much larger quantity of leaf under the action of hydrochloric acid 
— and, in fact, there was more general growth than by undecom- 
posed bone-dust, though but little tendency to form bulb ; yet 
there is little doubt that eventually, if allowed to mature, the 
decomposed bone-earth would have given much the largest 
amount of bulb as well as entire plant. 



AgricvJtural GfieTmstry — Twnips, 



35 



Snlphuric acid, as the decomposing agent, indicates in every 
case a considerably more rapid determination to bulb than either 
the nndecoraposed bone-earth or that acted upon by the hydro- 
chloric acid ; and, excepting where amraoniacal salt is superadded, 
there is a perceptible progression as the amount of acid is in- 
creased. Where the ammoniacal salt was used, though the for- 
mation of biiO) is not greater under an increase of acid, there was 
here, as in the case of the hydrochloric acid, a larger development 
of leaf. 

The effect of an equal amount of supei'phosphate of lime on 
land ploughed in the ordinary way, or which hswi been dug 9 or 
18 inches deep in the previous year, is here shown : — 





Avemge Weight of Bulbs, 


in lbs. 


Plot 
Koft. 


Land, how Tilled. 


Drilled 

Manures 

only. 


Drilled 
Manures, 

andlOcwts. 

Rape-cake 
per Acre. 


Drilled 
Mauurei^ 

and 3 cwts. 

Snlpli. Am. 
per Acre. 


Drilled 
Manures, 

and 3 cwts. 

Sulph. Am. 

and 10 cwts. 
Rape-cake 
per Acre. 


12 
14 
22 


Land dug 9 inches in 1844 (HI 
cwts. superphosphate of lime) i 

lAnd dog 18 incfies in 1844 (11 \ 
cwts. superphosphate of lime) | 

Land only ploughed (11 cwts. 1 
superphosphate of lime) ... ) 


1-20 
1-30 
M7 


1-39 
1-33 
1-33 


119 
1-30 
1-06 


107 
119 
1-17 



Excepting in column 2, the rapidity of bulb-fonnation is 
slightly the greatest where the land is deeply trenched, and in 
the exceptional case a larger development of leaf was found. The 
land dug 9 inches deep also shows a slight superiority over that 
which was only ploughed. The difiFerences are not quoted as 
offering any adequate advantage for so expensive a process as 
spade-digging; but the facts themselves help to indicate the 
character of tiie conditions required in turnip culture. 

We shall next show the result of the yearly supply of alJcalus, 
compared with that from a plot (No. 21) which had been 
drained of them by a course of ordinary cropping, succeeded by 
the removal of tw^o crops of turnips : — 

In the first two columns, where, as we shall presently show, the 
balance of organic constituents was more favourable to bulh-formar' 
tion than in the other cases, we find a greater development of 
bulb in an equal period of time by superphosphate of lime alone, 
than when the alkalies, either separately or united, were supplied 
with it. It 18 remarkable, too, that in No. 17, where potass was 
employed, there is a general inferiority observable. Again, of 
the several alkaline conditions, that where potass, soda, and mag- 
nesia are used together is the best. The differences exhibited 

D 2 



36 



Agricultural Chemistry — Turnips, 



Plot 
Kos. 



21 
15 

16 

17 

18 



Description of AUcaline Manures (drilled). 



400 lbs. calcined bone-dost, and 
400 lbs. snlphnric acid 

400 lbs. calcined bone-dust, 420 
lbs. snlphnric acid, and 315 
lbs. soda ash ... 

400 lbs. calcined bone-dnst, 420 
lbs. sulphuric acid, and 220 
lbs. Diagnesian limestone ... 

400 lbs. calcined bone-dust, 420 
lbs. sulphuric acid, and 470 
lbs. pearlash 

400 lbs. calcined bone-dust, 420 
Ibft. sulphuricacid, 105 lbs.soda 
ash, 74 lbs. magnesian lime- 
stone, and 157 lbs. pearlash... 

Mean by alkaline supply ... 



} 



Ayerage Weight of Bulbs, in Ibe. 



Drilled 

Manures 

only. 



1-22 
Ml 

Ml 

102 

116 



1-10 



Drilled ! Drilled 
Manures, | Manures, 

audio cwts. and 3 cwts. 

Bape-cake Sulph. Am. 
per Acra per Acre. 



1-41 
1-37 

1-35 

1-27 

1-33 



110 
114 

1-21 

1-16 

1-18 



DriUed 

Manorea, 

8 cwts. 

Salplu Am. 

and 10 cwts. 

Kape-cake 

per Acre. 



lis 

110 
114 
113 

1-25 



1-33 



1*17 



116 



are at any rate sufficient to show that there was no advantage 
derived by the use of alkaline manures in this soil, which had 
been subjected to an unusually severe exhaustion of them. 

We have, indeed, uniformly observed, not only in the case of 
turnips, but of other plants, that by the direct supply of alkalies no 
good effect has resulted in the season of the application, though 
the succeeding crops have apparently, to a small extent, been 
benefited. It is our opinion that, in the ordinary course of 
farming, the special supply of alkalies to the soil is exceedingly 
rarely requisite, — and, if ever it be so, they should never be ap- 
plied in an aikaliTie condition (which seems to be very prejudicial 
to healthy vegetation), but always supersaturated by acids. Fur- 
ther, alkalies should not be drilled, but should always be sown 
broadcast, and well incorporated with the soil. In the case of 
turnips especially is this to be carefully attended to ; and, indeed, 
it might be almost laid down as a general rule, that those manur- 
ing substances which take their value as mere constituents of the 
plant (alkalies and organic manures), should be well distributed 
through the soil ; and those which further exercise an influence 
upon the health and vigour of the plant, such as superphosphate 
of lime, should be drilled near the seed. 

Whether or not superphosphate of lime owes much of its effect 
to its chemical actions in the soil, it is certainly true that it causes 
a much-enhanced development of the vndergroimd collective appa- 
ratus of the plant, especially of lateral and fibrous root, distri- 



Agricultural GJiemishy — Turnips, 



87 



bating a complete network to a considerable distance around the 
plant, and throwing innumerable mouths to the surface. The ex- 
tent and direction of the undergrovnd range of the turnip are at 
the same time very much dependent on the mechanical condition 
of the soil : and it is universally known that tiUh is of the highest 
importance to the favourable formation of hilh. We know that 
the best relation of bulb to leaf, and, in fact, the best acreage 
produce of bulbs is in the lighter soils, where there is compara- 
tively little obstruction to the development of fibrous root, and it 
is in these that the special efficacy of superphosphate of lime has 
been most observable. We believe that, if the turnip is to be 
valued for its hvlb^formation^ the aim of our culture must be, not 
to increase the abovpground organs of collection (the leaves), but 
the uriderground fibrous roots. 

We shall now consider the effects of *' o^'ganic manures " upon 
the production of turnip-bulb ; and the facts that will come before 
us will tend to confirm the views just maintained regarding the es- 
sential development of rootlet- rather than leaf-accumulation, as a 
means of obtaining the turnip in agricultural quantity and quality. 

The results collected below will illustrate some of the effects 
of " organic manures " upon the growth of the turnip : — 





Average Weight of Bnlbe, in lbs. 


Description of Mineral Manures. 


Mineral 

Manures 

only. 

1-16 
110 
1-21 


Mineral 
Mannres 

and 10 owtfl. 

Rape-cake 
per Acre. 


Mineral 
Manures, 

and 3 owts. 

Sulph. Am. 
per Acre. 


Mineral 

ManurcH, 

10 cwts. 

Rape-cake 

and 8 cwts. 

Sulph. Am. 

per Acre. 


Mean of entire series of poreljl 
mineral manures 

Mean of four experiments withi 
alkaline snpply 

Mean of three experiments with! 
superphosphate of lime j 


1-31 
1-33 
1-37 


114 

117 
1-18 


110 
116 
113 



We may explain that the results in the first column were ob- 
tained hj means of mineral manures alone, and that, the previous 
crops having been entirely removed from the land, the organic 
supplies must have been chiefly derived from the atmosphere. 
The development of leaf was less in these than in any of the other 
cases. In column 2 there was, besides these same mineral man- 
ures, 10 cwts. rape-cake, which may be estimated to provide 
perhaps 50 lbs. of nitrogen. It was, however, employed in these 
experiments as supplying a large amount of carbonaceous matter, 
in which it abounds. In the 3rd column the eflects are due to 
the addition of 3 cwts. of sulphate of ammonia to the mineral 
manures. In these cases about 60 lbs. of nitrogen is supplied, 
but no carbon. In the 4th column we have the effects of the 



38 



Agricidtural Chemistry — Turnips. 



addition both of the rape-cake and of the ammoniacal salt to the 
standard mineral manure ; consequently the supply of nitrogen 
by manure would amount to about 110 lbs. per acre. 

It is seen that, whichever mineral condition be taken, the sup- 
ply of carbonaceous matter has given the largest bulb. Of the 
two mineral series, the acid and the alkaline, the former exhibits 
a general superiority in each case, excepting in the 4th column, 
where the defect is very trifling. In this case, notwithstanding 
there was a carbonaceous supply equal to that in column 2, the 
excessive amount of nitrogeiioiLS matter has prevented a favourable 
formation of bulb. These mean results clearly show that carbon- 
aceous rather than nitrogenous organic supply is favourable to 
hulh-formationj and the fact is confirmed by the following indi- 
vidual cases : — 

Selected Results. 





Description of Drilled Manares. 


Average Weight of Biilbs, in lbs. 


riot 

Kos. 


Drilled 

Manures 

only. 


Drilled ' DriUed 
Mnnnrefl, Manures, 

andlOcwts. and S cwts. 

Ilaf)e-cake Solpti. Am. 
I)er Acre, per Acre. 


DrUletl 
Mannres, 

lOCWtK 

Kape-cake 

and S cwti. 

Sulph. Am. 

per Acre. 


18 
19 
20 


Superphosphate of lime, with ' 
potass, soda, and magnesia... 

As No. 18, and 1 cwt. sulphate 1 
of ammonia j 

As No. 18, and 3 cwt. rape-cake 


116 

116 

1-28 


1-33 ' 118 

1 

1-24 , 102 
1-40 118 


1-25 

109 
118 



In all these cases the mineral manure was the same, and, in all, 
the 2nd column under the cross-dressing of rape-cake shows the 
best result. Further, looking at each column separately, we find 
that No. 20 always gives a heavier bulb than No. 19, and, ex- 
cepting under the cross-dressings of ammoniacal salt, than No. 18 
also. The amount of the differences is not indeed great ; but 
when we remember that the results are calculated from nearly 
2000 plants in each case, their uniformity and constancy demand 
that reliance should be placed in them. It is clear, then, that 
carbonaceous manures aid the development of turnip-buU). We 
shall give one more quotation on this subject : — 



No drilled manure (third season)... 



Average Weight of Bulbs, in lbs. 



No Cross- 
dre»siiig. 



Oil 



Crofw- 

dresRotl 

by 10 cwts. 

Kape-cake 

per Acre. 



CroRS- 
dreui^ed 
by S cwta. 
Sulphate 
Ammonia 
por Acre. 



0-67 



007 



Cn)8s- 
dre»seti 
by 10 ovrts. 
Rape-cake 
and 3 owt«. 
Sulph. Am. 
per Acre. 

0-50 



ITie instances before us are of high interest in many points of 



ArfrintUural Cheinisiry — Turnips, 



39 



view, but we are not prepared to consider them fully until we 
have detailed the results of an analytical examination of the 
crops — a subject which we shall presently enter upon. Resuming 
the question in discussion, we see that whilst ammoniacal salts in 
no degree restored fertility to this exhausted soil, rape-cake gave 
a six-fold development. In the 4th column, under an equal 
amount of rape-cake, we find as usual that the excess of nitro- 
genous manure has deteriorated the tendency to bulb formation 
exhibited in column 2. 

The contrast observed in the effects of ammoniacal salts upon 
wheat and upon turnips is very remarkable, and aflTords a striking 
illustration of the widely differing requirements and sources of 
growth of the corn-exporting " white crops," and the home-con- 
sumed, meat-producing "green" or "fallow crops," of which 
classes, respectively, the two plants may be considered as the 
types. 

Hitherto we have only considered the effects of organic 
manures upon the formation of tumip-feuZfe, the amount of which 
is thought to determine the value of the crop when cultivated 
for feeding and rotation purposes. It has been seen that a 
liberal supply of available phosphates and of organic manures 
abounding in carbonaceous matter are pre-eminently favourable 
to the desired habit of the plant, and that nitrogenous supply, 
so essential to the increased growth of com, is so here only to a 
very limited extent. Under the influence of ammoniacal 
manures, however, the production of turnip leaf is much en- 
hanced, as the following results will show : — 





















I^roportion 

^ m Ml 


Deacription of Maniires. 


Bulb per 


Acre, 


in 


Leaf per 


acre, 


in 


Of lA*Slt to 

KXK) of 




Tons. 
















Bulb. 




cwts. 


qra. 


lbs. 


Tons. cwts. 


qr& 


lbs. 




Mean by pnrely mineral manures 


12 


8 


2 


3 


4 


4 





14 


326 


Mean of mineral manures, with ) 
10 cwts. rape-cake added ... 


13 


4 


2 


20 


5 


12 





21 


421 


Mean by mineral manures, and 




















3 cwts. sulphate of ammonia - 
aflQcu ... ••. ... ... ...' 


11 


18 


1 


24 


6 


16 





21 


559 




















Mean by mineral manures, and | 




















3 cwts. sulphate of ammonia 


12 


6 





13 


5 


14 





17 


466 


(second gathering) ) 


1 


















Mean by purely mineral man- ^ 


















nres, and both rape-cake 


11 


6 


1 


11 


7 


9 





22 


669 


and ammoniacal salt 




















Mean by purely mineral man- \ 
urcs, and both rape-cake [ ,o 
and ammoniacal salt(second 
gathering) .../i 


















4 


3 


6 


6 


16 


2 


16 


554 



















Thus, comparing lines 1 and 3, we find that whilst, by the addi- 
tion of ammoniacal salt in the latter case, there is in an equal 



40 Agricultural Chemistry — Twmips. 

space of time half a ton less of bulb, there is an increase in leaf 
by 2^ tons ; and, as shown in the 3rd column, the proportion of 
leaf to bulb is more than half as much again. TcJ^ing lines 2 
and 5, the addition of ammoniacal salt, as in 5, gives nearly 2 tons 
less bulb, but nearly 2 tons more leaf, the proportion of leaf to 
bulb being again increased by one-half. The gross produce is 
seen, therefore, to be greater in one of these cases, and as great 
in the other, under the addition of ammoniacal salts. We have 
before remarked, however, that whilst at the time of gathering, 
the crops by mineral manures alone, as in line 1, had probably 
more than fully arrived at maturity — the leaves having drooped 
and changed colour — those under rape-cake addition only had 
but just attained full growth, and those having ammoniacal salts, 
as in lines 3 and 5, evidently possessed yet unexhausted vitality, 
especially in No. 5, the case where rape-cake was also supplied. 
It might be supposed, therefore, that in due course bulbous de- 
velopment would succeed as the increased leaves drooped. The 
results of the second gathering, taken when the leaves under am- 
moniacal salt without rape-cake had considerably fallen (those 
with it being still vigorous), show this to have been the case to a 
greater or less degree. A comparison of lines 3 and 4 shows an 
increase of bulb in three weeks of 7 cwts., at the expense of 19 
cwts. of fresh weight of leaf. On the other hand, line 6 gives an 
increase in the same period of 18^ cwts. of bulb, at the expense 
of only 14 cwts. of fresh leaf. Under ammoniacal salts alone 
there had therefore been an actual depreciation in fresh weight, 
indicating at least a loss of vitality, though there was probably 
no real loss of solid matter. Where there was rape-cake also, 
however, we find an actual gain in gross weight, and we had un- 
doubtedly a vitality and resource of growth still unexhausted. 
Comparing line 4 with line 1, the latter has still the largest 
weight of bulb ; and comparing line 6 with line 2, the former is 
still a ton in advance. Were we to admit, however, that if the 
crops could have been taken each at the stage of its best yield of 
huU)^ there would have been a slight superiority under the nitro- 
genous manuring, the quantity yielding the eifect in these in- 
stances could in no form have been economically obtained, even 
were there no other objection to its use. 

The effects of an excess of nitrogen in tending to an unprofit- 
able habit of the plant are further exhibited in page 41 : — 

It is here seen that whilst farm-yard dung, itself containing 
some nitrogen, and certainly a very full allowance of carbonaceous " 
matter, givres 17 tons of bulb, we have more than 2 tons less bulb 
when ammoniacal salt is superadded ; but there are at the same 
time 3 tons more leaf than by dung alone. The 3rd column 
shows that the actual size of bulb, as well as its acreage produce, 



AgricuUtircd Chemistry — Turnips. 



41 





Bulb per Acre, in 


Leaf per Acre, io 


Average 

Weight of 

Bulbs. 


Proportion 

of Leaf to 

1000 of 

Bulb. 


12 tons farm-yard dang 
1 2 tons f ann-yd. dnng, ' 
and 3 cwts. sal-  
phate of ammonia . 


Tods. cwts. qrs. lbs. 
17 3 6 

U 18 3 12 


Tons. cwts. qrs. lbs. 
7 7 3 2 

10 8 3 12 


1-61 
1-45 


433 

700 



was less, under the excessive supply of nitrogen ; the 4th, that 
under the same circumstances the proportion of leaf to bulb was 
increased by more than one-half. So far as supply of constUvsnts 
is concerned, we could select from the series of experiments 
several instances where we may reasonably suppose that every 
constituent, excepting carbon, existed more fully in quantity and 
more favourably in combination than in the dung, yet with its 
larger carhonaceovs supply to the root we get the largest crop of 
bulb in the series. The excess of nitrogenous manure, however, 
is seen greatly to enhance the leaf-forming tendencies of the 
plant, which it is true may probably aid carbonic acid accumu- 
lation from the atmosphere, but at the same time gives a less 
profitable appropriation of the resources within the soil ; and we 
shall afterwards see it to be by no means clear that there is with 
a large production of leaf a proportional gam of nitrogen from 
the atmosphere. 

Admitting, then, that the organic manure required for the 
growth of twrnv^hulbs should be carbonaceous rather than nitro- 
genous, there is still evidence that, under the influence of a due 
provision of nitrogen, the vitality or longevity of the plant is 
greatly increased f and since the turnip crop is required to brave 
the winter frosts, an early and perfect ripening, such as would be 
induced by a defect of nitrogen relatively to carbon, whilst it 
might be coincident with a more rapid bulb formation, would by 
no means be a desideratum. We believe, however, that in the 
ordinary course of farming, the special supply of nitrogen to the 
turnip crop, by means of artificial manures, is seldom if ever 
necessary ; for there is no ample source of available carbon which 
does not provide at the same time a considerable amount of 
nitrogen. As, therefore, in the case of wheat, we need not study 
the supply of carbonaceous manures, so, in the case of turnips, it 
comes to be unnecessary to devote special care to the provision of 
nitrogen. In the one case the means adopted specially to secure 
nitrogen to the soil, brings with it enough of carbon ; and in the 
other the peculiarly carbonaceous manures are associated with 
sufficient nitrogen. 

We have argued that for the growth of tumip-&wft a soil is 



. 42 Ag^^icidtiiral Chemistry — Turnips, 

required in such a mechanical condition as shall render it easily 
permeable to the atmosphere and to the fibrous roots of the 
plants, — that healthy action and a tendency to development of 
very extended underground collective apparatus should be in- 
duced by the use of the so-called ** mineral manures," these never 
being in an alkaline state, and always containing a considerable 
quantity of phosphoric acid easily available to the plant, — that 
after the early stages of the plant are passed, its rapidity of growth 
depends upon an abundant provision m the soil of constituents for 
organic formations, especially of carbon^ — that nitrogen must be 
provided by cultivation, though seldom by special manures, — 
and lastly, that all these requisites being provided by the farmer, 
the degree in which his efforts will be availing depends essentially 
upon certain climatic conditions, comprising a considerable con- 
tinuity and amount of rain, as a means of taking up the stores 
of the soil, keeping up a vigorous circulation in the plant, and 
supplying the dissolved gases of the atmosphere. 

These conditions compared with those which are required in 
the culture of wheat are opposed to one another in almost every 
particular, but as we proceed we shall see, that of the observed 
differences much is doubtless due to the essential distinctions 
between the tendencies of the natural families to which the plants 
belong ; yet much of it is also attributable to the fact, that in the 
case of the turnip it is not the seed that is the object of onr 
culture, but a monstrous accumulation which could only take 
place under a somewhat unnatural or artificial balance of the 
constituents of supplied food, and under such a condition of 
climate as should be adverse to seed-forming. 

It is known that where the turnip is grown for its natural seed- 
product, oil, a heavier soil, richer manuring, and, during a con- 
siderable period of the growth of the plant, a much higher 
I temperature, are required than when the bulb is -to be produced. 

Under these circumstances there will be much less fibrous root 
thrown up to the surface, — the root is scarcely bulbous, but fusi- 
form, tapping rather than spreading laterally ; the leaves and 
stem are much larger, both actually and proportionally to the 
root, and the organic manures should contain more nitrogen and 
less carbon. Were we then to cultivate the turnip for its most 
natural products, the treatment it would require would much 
more nearly approach that adapted for wheat than at present ; 
the deviations from it now observed, and which have been referred 
too exclusively to the natural specialities of the plants, would be 
greatly lessened, and the character of the plant as a ^^ fallow crop " 
would be lost. It is no objection to this assumption that in 
selecting plants to transplant for seed from which to grow IruUb^ 
those liaving the most symmetrical bulb are chosen rather than 



Agricultural Chemistry — Tiimips. 43 

such as are more fusiform, and betray a more abundant seed- 
forming habit — in this case it is not the most abundant natural 
seed that is the object of culture, but a seed having a special 
habit of growth, which habit it is wished to propagate. 

There being an evident understood subserviency of the leaf of 
the turnip to the bulb, and a sort of succession in the order of 
maturation of these different organs, the latter not being perfected 
until the former has lost much of its succulence and vigour ; this 
fact, and the special conformation of the plant, as before adverted 
to, have, in theory, led to an appreciation of forcing a large 
amount of leaf, which is not consistent either with the full 
efficiency of the conditions which our researches show to favour 
6«ft-formation, with the character of the soils best suited to the 
growth of the turnip-bulb, or that of the plant which is most 
approved by the practical agriculturist. It is true that rela- 
tively to wheat and many other plants, the turnip exhibits a large 
eurface of succulent leaf, which it is admitted indicates a greater 
reliance in one way or other upon the atmosphere ; yet all expe- 
rience, when judging not between the turnip and other plants, 
but between one turnip and another turnip, values the one in 
which the proportion of leaf is least and the tendency to bulb the 
greatest. The description of soil which is called a turnip-soil, 
again, is just that which is best adapted to formation of fibrous 
root, and that which always yields a proportionally small amount 
of leaf. Moreover, the soils which yield the largest amount of 
leaf are known not only by their general mechanical condition, 
but by their comparative richness in nitrogen, to be exactly those 
in which the results of our experiments would lead us to anticipate 
that the leaf-forming tendency would predominate. In these too, 
as compared with the lighter ones, an excess of nitrogen in the 
manure is the more likely to give an undesirable development, for 
in the latter any increased vigour of growth arising from nitro- 
genous agency may more easily extend the underground organs 
and determine to bulb-formation than in the former. 



We have now given a history of our experiments upon turnip 
culture during the first three seasons of their course, so far as the 
conduct of them in the field is concerned, though none, as yet, 
of the results obtained in the two succeeding seasons, the last of 
which is now drawing to a close. Details of this kind having, 
however, already taken up much space, and suflSced, we hope, to 
elucidate some established rules of practice, we shall defer until 
a future occasion a further consideration of this branch of our 
evidence, and enter at once into an account of our researches in 
the laboratory, as tending not only to confirm or confiite con- 



44 Agricultural Chemisby — Ihmiips. 

elusions otherwise arrived at, but as opening out points of interest, 
both in science and in practice, not hitherto brought to view. 

The atmosphere and the virgin soil being originally the exclu- 
sive sources, the former of the *' organic,' and the latter of the 
" inorganic " or ^^ mineral" constituents of plants, it has been sup- 
posed that the amount of produce which a given space of ground 
would yield must depend upon its richness in those substances 
proper to itself, namely, the mineral constituents ; and that these 
being supplied in full quantity, according to the indications of the 
analyses of the ashes of the crops it is wished to grow, the atmos- 
phere would always prove an ample available resource for the 
more peculiarly vegetable matters. It will be readily understood 
that on such a view as this, economy in agriculture would be 
attained by a very different course of practice from that required 
were it to be shown that cultivation should effect an artificial 
accumulation in the soil of those constituents primarily derived 
from the atmosphere, rather than of such as more especially 
belong to its own constitution. 

The theory referred to has led to the analysis of the ashes of a 
great many agricultural crops, and upon the data thus obtained 
(rather than upon a consideration of the requirements actually 
induced by an artificially enhanced vegetation, or of the real 
source and destination of the constituents under a course of prac- 
tical agriculture), recommendations to the agriculturist have been 
founded, the validity of which it was desirable should be tested 
by actual experiment, as well as by the presumed dictates of ex- 
perience. The field results which we have detailed, both upon 
the subjects of wheat and of turnips, are unfavourable to these 
opinions and recommendations, and analysis will be found to bear 
testimony in the same direction. 

A knowledge of the composition of our crops, as affected by 
climate and cultivation, is however of great importance, not only 
as showing what are the sources which must be relied upon for 
the various constituents, but as assisting a judgment of the feed- 
ing value of the produce, and of the economy of the means to the 
adoption of which the variations in composition may be traced. 
It is more especially with a view to these points of interest that 
our results have been sought, and that their bearings will be now 
considered. 

In the course of an analytical examination of an agricultural 
specimen, the first steps are to determine the percentages re- 
spectively of dry vegetable substance and of mineral matters. For 
this purpose a known weight of the produce is exposed for a 
length of time to such a temperature as will only expel all the 
water it contains ; a portion is then burnt to an ash, which is 
presumed to retain all the " mineraZ," but none of the '^vegetable" 



Agricultural Chemistry — Turnips. 45 

substances of the specimen, the latter having been consumed and 
yaporized by the burning process. The knowledge which these 
simple experiments may aflford is never to be overlooked in con- 
sidering the composition of an agricultural product, and estimat- 
ing its probable value, or the economy of the manuring, or 
other means which have been employed in its growth. A judg- 
ment formed thus alone, however, of the comparative characters 
of different specimens would be fallacious, owing chiefly to the 
facts that the dry matter of different specimens of the same kind 
Off plant may differ much in composition, and that a very large 
proportion of our agricultural produce is not allowed to ripen its 
seed and attain a somewhat fixed condition of dryness not 
materially affected by collection, storing, and transmission, but 
is taken whilst the vital circulation of the plant is still proceeding 
with considerable vigour, causing, long ailer removal from the 
land, a rapid exhalation of watery vapour, tending very much to 
mislead as to the amount of dry matter really contained in the 
substance under examination. Unless, then, a series of such 
specimens — the comparative characters of which are to be esti- 
mated — be treated in every respect similarly, as to time of 
gathering, weighing, &c., serious errors must occur. 

When ultimate ripened products are the subjects of examina- 
tion, there is little difficulty in conducting a series of drying ex- 
periments, 80 that the results shall be true indications of the 
differences really dependent on climate and culture ; and although 
in SQch cases the range of variation in the amount of dry matter 
is small, yet the variations themselyes are very significant, be- 
speaking at once the conditions of growth, and, within certain 
limits, the probable qualities of the products. 

There can be little doubt that, after reliable standards have 
been fixed, a knowledge of the true undoubted percentage of dry 
matter in specimens of green produce also might materially aid 
our judgment of their other characters ; but, as yet, neither have 
we these standards, nor are the methods of different experimenters 
80 uniform that their results can compare one with another. So 
little, indeed, is really fixed and generally admitted regarding 
both the methods of and the proper inferences from such experi- 
ments, that the results of the same operator will, in his own view, 
be the more doubted the more he learns of the lesson they are 
calculated to teach ; and before there can be any common argu- 
ment or comparison conducted on such subjects, there must be 
some uniformity of method agreed upon. In illustration of this 
necessity one or two experiments only are needed. 

A quantity of turnip leaves were taken direct from the field 
to a bam about sunset, and were immediately weighed into lots 
of 25 and 50 oz. each. These bundles were laid upon straw, and 



46 Agricultural Ghemistry — Turnips, 

on re- weighing the following morning were found to have lost 
more than 6 per cent. If the leaves gathered in the evening had 
not been weighed for drying until the following morning, an error 
of 1 per cent, or more in the estimation of dry matter would thus 
have arisen. We have elsewhere stated that 100 oz. spe<;imens 
of green wheat-plant lost invariably from 7 to 9 per cent, during 
the process of separating from each other the leaves, the ear, and 
the stem, although two persons were employed in the operation. 

Again, five turnips, with their leaves, were found to weigh as 
soon as gathered 16 lbs. 4^ oz. ; after exposure two days and 
nights upon straw, under cover, they weighed 15 lbs. 5^ oz. ; 
and after three days and nights more, 14 lbs. 8^ oz. Thus, if 
after being gathered 48 hours, 100 oz. had been taken for a 
drying experiment, it would have been equivalent to 106 oz. of 
fresh plant ; and if after five days, to 112 oz. Five plants were 
next taken, and the leaves cut off, leaving, perhaps, two inches of 
stem upon the bulbs. The turnips, thus freed of their leaves, 
weighed 12 lbs. 8^ oz. ; after 48 hours on straw, under cover, 
12 lbs. 4^ oz. ; and after 3 days more, 11 lbs. 3f oz. In this 
case, 100 oz. taken aft»r being gathered 48 hours would have 
represented 102 oz. fresh bulb ; and after 5 days, 106 oz. These 
turnip experiments were made in cold October weather ; but the 
amount of loss sustained would of course depend much upon 
the vigour of growth of the plant, upon the state of the weather 
at the time, and the temperature of the place where the plants 
were kept. 

It is evident, then, that very serious errors may arise when 
specimens are received from a distance, or even when they are 
not, unless special precautions be taken, according to the nature 
of the produce under examination. Indeed it is exceedingly 
diflScult when fully aware of these circumstances, so to conduct 
an extensive series of comparative experiments on green or suc- 
culent substances as to obtain results which shall be both actually 
and relatively to each other open to no objection. 

When, in the experiments quoted above, bulbs with the leaves, 
or the leaves alone are taken, the loss is seen to be much greater 
than when the bulbs alone are operated upon. This is what 
might have been anticipated, and shows clearly that the efiect is 
due to the continuance of the natural circulatory processes of the 
leaves after removal from the land. 

In operating upon bulbs or roots which are in contact with the 
soil, we meet with a difiiculty of another kind. In such cases 
there is always a quantity of soil adhering to the specimens, 
which, if not removed, will affect to some extent the determination 
of dry matter, and still more seriously that of the mineral matter. 
A single bulb may be cleaned sufficiently by careful picking and 



Z. 



AgriaiiUural Chermstry — Turnips, 



47 



wiping, bnt an extended series of determinations cannot be oon- 
ducted under equal circumstances and with the necessary despatch 
without washing, by which soluble substances may to some extent 
be removed, or an absorption of water may take place. With 
the view of ascertaining the degree of error to which the washing 
of bulbs for drying and burning may lead, six lots, consisting 
each of five turnips, were taken, and the leaves were cut off, 
leaving a sufficient handle ; three of the lots were carefully cleaned 
without the use of water, the other three being scrubbed with 
a brush in water, in which they were allowed to remain for ten 
minutes or a quarter of an hour ; they were then taken out, rubbed 
dry with a cloth, sliced, and weighed. After exposure to a tem- 
perature of 212® for a sufficient time, the percentages of dry 
matter were as under : — 




Without 
washing. 



8*36 
803 



7-64 



With 
washing. 



7-96 
7-79 



7-30 



Average 8*01 



7-68 



There was evidently some difference in the specimens them- 
selves, but the w^irshing process gives in the main a less per- 
centage of dry matter than the other. Without washing there 
must always be expected a small excess, and with it a slight de- 
ficiency. In the particular instances quoted the deficiency was 
likely to be greater than in the usual conduct of the process, as 
the operation was purposely rather prolonged, that the extreme 
effects might be ascertained. It is admitted, however, that wash- 
ing is an objectionable procedure ; but when drying and burning 
experimente are conducted on an extended scale, the results will 
be more uniform in character and more comparable one with 
another than were any other method adopted, as all such either 
take up so much time that the specimens must, with the risk of 
change of weather, be collected at different times, or so many 
persons must be employed that the desirable suiTcillance is 
impracticable. 

Having given thus far some general statement as to the manner 
in which our drying results have been obtained, those of our 
readers who understand such matters will be able to decide for 
what purposes our figures may be relied upon, and wherein they 
are likely to be wide of the exact truth. For ourselves, we are of 
opinion that, taken in series rather than individually, they may be 
trusted in discussing any points with which our general knowledge 



48 AgncuUural Cliemistry — Turnips. 

of such subjects will lead us to deal, and that they very closely 
represent the exact facts. 

The following dry-matter results (p. 49) refer only to the pro- 
duce of the third year's experiments (season 1845), The entire 
series is tabulated. 

Were we to consider each of these results seriativiy with a view 
to trace the variations in the produce to variations in the compo- 
sition of the mineral or of the organic manures, we should find nu- 
merous exceptions to any generalization to which we might thus 
be led. When we look, however, at extreme instances, or at 
series strictly comparable one with another, we cannot fail to 
see some undoubted general connexion between the amouiit 
of dry matter on the one hand, and such character or stage 
of growth as we have already observed to result from certain con- 
ditions of manuring on the oiher. We must be careful, however, 
to bear in mind the nature of the substances on which we have 
been operating, and the various circumstances which have been 
pointed out as tending to vitiate the legitimacy of any compari- 
sons ; otherwise we may place undue reliance on single results, 
or, finding these discrepant with others, come to the conclusion 
that we have no lesson taught us by so extensive and laborious 
a course of experiments. With our present limited knowledge, 
it is, moreover, desirable to exercise great caution in applying 
to practice the indications of results of this kind. 

It must be remembered, then, that the turnip plant cultivated 
as food for stock is gathered at no well-defined stage of its 
growth, but whilst containing a vast amount of circulating fluid, 
the proportion and concentration of which is subject to constant 
variation under the influence of the still active vital processes of 
the plant, the varying stores of moisture and of food presented 
to the roots, and the circumstances of temperature, light, and 
moisture of the atmosphere, to which the leaves are exposed. 
In fact, we might liken the growing turnip to an animal whose 
gross composition would vary according to his resources of food 
and drink, and the condition of exhaustion or waste to which he 
is exposed. At one time his stomach and blood-vessels are full, 
and at another their contents bear a much lessened relation to 
the more fixed portion of the body. 

The water existing in the Norfolk-white turnip-bulb is seen to 
constitute more than nine-tenths of its entire weight ; and if it 
should appear that the proportion varies according to the stage of 
growth, it will be admitted that the degree of maturity of a suo- 
culent plant which is to be the subject of a drying experiment, 
must be regarded, in deciding its probable yield of solid food, as 
resulting from various manures ; for if the amount of water is 
found to decrease accordingly as the plant matures, that one which 



i 


ijfi 


A/jricuUuml Chemstry—Tumiips. 

zititllt z tiiliiil e iiss 


49 


1 


ifif^i 


?lg??s|? ? s;gii;i£ ! !I5e 


1 

S 


1 


m 


SiSssili 1 isilsEEl 1 Silt 


1 
i 

i 
i 

B 

S 

t 
s 

1 
1 

I 
1 


lit 


lifisilsisisEliiSslisi 



50 



Agricultural Chemistry — Turnips, 



afiJer an equal period of growth is found to contain most water 
would, conditionally, indicate a more extended farther growth, and 
the manure under which it had grown might be better rather than 
worse than that to which the more solid turnip owed its character. 
Agaii\ ; a series of plots under different manures, though they 
will be characterized by an undoubted difference in the stage of 
maturity of the plant, will each within itself exhibit a wide range 
of variation in this respect, and it is impracticable to gather spe- 
cimens which shall certainly and exactly represent the characters 
induced by the manuring of the plots. In our experiments, from 
tek to twenty plants of average size, and which appear to be sound 
and firm, are selected from each plot, and from these, when 
washed and sliced, a weighed quantity is taken ; in some cases 
100 oz., and in some 150 oz. ; in some more, and in some less. 
The results given in the table were obtained from specimen lots 
of 150 oz. each, and the soil, season, variety of turnip, and time 
of sowing and gathering, were the same throughout.* 

Prom these remarks, our readers will be able to judge for 
themselves whether too much or too little is based upon our re- 
sults. We feel, however, that it will be much more conducive to 
the interests of agriculture that the error should be in the latter 
rather than in the former direction. 

The following mean results exhibit the general bearings of the 
experiments more clearly and safely than individual selections 
would do : — 





Dry Matter, per cent. 


Deacription of Drilled Mannrea. 


Drilled 

Manares 

only. 


Drilled 

Man ares, 

and Top- 

drcaslug of 

Kape-oake. 


Drilled 

Manures, 

and Top- 

dreesinff of 

Amm. Salt. 


Drilled 
Manures, 
and Top- 
dressing of 
Rape-cake 
and Amm. 
Salt. 


Mean of 13 purely mineral manures... 
Mean of 4 experiments with alkaline i 

phosphates i 

Mean of 3 experiments with super- \ 

phosphate of lime f 


8-34 
8-28 

8*09 


7-97 
7-90 

7-97 


7-41 
7-67 

7-60 


7-48 
7*63 

7-36 



These means show a striking uniformity in the amount of dry 
matter in each column taken separately, — that is, under the influ- 
ence of various mineral manures, but a like resource for organic 
formations. Comparing column with column, however, we find 
a difference which, though not actually great, must be admitted 
to have some meaning, when we bear in mind the uniformity 
within the columns themselves. Were we to compare these 

* The conditions of manuring alone were different, and we may therefore 
rely upon the general indications of the experiments, so far as the effects of 
manures are nonoemed. 



Agricultural Ghemisiry — Turnips. 



51 



effects of organic supply upon the percentage of dry matter with 
those of the same conditions upon the average acreage produce, no 
correspondence, either direct or inverse, would be clearly defined ; 
for we see in the table just given a pretty uniform depreciation 
from the first column to the third, and the fourth is not wide of 
the third, but the acreage amounts of produce were as under : — 

AvBHAOB Acreage Prodnce of Balb, in toDs, cwts., qrs., and lbs. 



DriDed lianiirea only. 


DriUed Manures, 

and 

Top-flreasing of 

Rape-cake. 


Drilled Mannrefl, 

and 
Top-drcaeing of 

Amm. Salt. 


Drilled ManoreB, 

and Top-dressing of 

BapC'Oake and 

Amm. Salt. 


ToDfi. cwUl qra. Ibfl. 
12 8 2 3 


Tons. cwte. qrs. lbs. 
13 4 2 20 


Tons. cwts. qrs. lbs. 
11 18 1 24 


Tons. owt& qrs. lbs. 
11 6 1 11 



We have before stated, that at the time of the first gathering 
of the crops, a short time prior to which the specimens for 
analysis were taken, the plants growing by purely mineral 
manures were very markedly the ripest, their leaves having 
much drooped ; next in order, in this respect, came those having 
T&pe-cake in addition ; then those having sulphate of ammonia ; 
and, lastly, those with both rape-cake and ammoniacal salt. 
The proportion of leaf to bulb at the time of weighing shows 
this to some extent. It was as under : — 





Drilled 

Manures 

only. 


. Drilled 
Manures, 
and Top- 
dressing of 
Bape-cake. 

421 


Drilled 

Manures, 

and Top- 

dreiising of 

Amm. Salt 


Drilled 

Manures 

and Top 

dressing of 

R>ipe-cake 

and Amm. 

Salt. 


Proportion of leaf to 1000 of bulb 


326 


559 


669 


Mean percentage of dry matter... 


8-34 


797 


7-41 


7-48 



We have, then, the largest amount of dry matter with the 
ripest bulb and poorest supply of organic manure, very nearly 
the smallest amount of dry matter with the plants least advanced 
to the point of heaviest bulb, but which had the largest stores 
of food in the soil, and probably the prospect of the longest life 
and fullest eventual growth, at least of entire plant, if not of 
bulb itself. The second weighing of the crops did indeed show 
in this case an increase in bulb and a decline in the proportion 
of leaf to bulb. Here, then, the influence of manures is in- 
direct ; for the proportion of dry matter is seen to be mainly 
dependent upon the degree of maturity of the plant, — ^and that 
this is affected by manures has been already shown ; and since 
the largest proportion of dry matter may show an early advanced 

 2 



52 Agricultural Chemisiry — Turnips. 

stage of maturity, frequently arising from an exhaustion of the' 
materials of growth, it may in fact bespeak the worst manuring 
condition, all other circumstances being equal. It is evident* 
then, that, even supposing the percentage of dry matter to be an 
unconditional measure of the feeding value of any particular spe- 
cimens, no comparison could be drawn respecting the eflSciency 
of the manures by which they were grown, unless every other 
condition, whether of season, soil, maturity, or variety, were con- 
sidered in their influence ; and then, indeed, the effects of the 
manures may be due to a forcing rather than to a supporting 
power. We shall have further proof, however, that the amount 
of water existing in the turnip depends upon the proportion of 
circulatory to the more fixed matter, and that as the plant 
matures that of the former diminishes and that of the latter 
increases; and it will also be seen that equal weights of dry 
matter may differ very greatly in probable nutritive value. 

Before leaving the results of the table, we may observe that by 
this series of nearly 100 different manures, the utmost variation in 
the proportion of dry matter in the Norfolk-white turnip-bulb 
is, after an equal period of time, 265, or about 2^ per cent., 
notwithstanding that there was a vast difference in the stage of 
maturity of the plants ; and it is thought that if the specimens 
could have been taken each at the point of its fullest growth, the 
variation strictly dependent on manures would have been much 
less. The highest percentage of dry matter in the entire series 
is 9*3, — all the rest are below 9, more than half below 8, and 
several below 7 ; the limit of difference, even under the actual 
circumstances, is, however, in by far the larger number of cases 
within 1 per cent. Boussingault gives 7*58 per cent., which 
agrees pretty well with our determinations, the mean of which is 
7*83; other observers having found a range in the proportion of 
dry matter of the turnip-bulb from this amount to nearly double, 
have attributed much of the variation to the conditions of man- 
uring; but the foregoing facts, in conjunction with those we 
shall now state, will show that no judgment of the effects of 
manures in this respect can be formed unless the experiments 
are made with the same variety of the plant. 

The specimens here referred to were grown in different fields, 
and by different manures, and several of them in the ordinary 
course of the farm. The 90 lots of experimental Norfolk- whites 
give a number for the mean percentage of dry matter identical 
with that found under farm-yard dung, and their extreme varia- 
tion is 2*65. The two specimens of green common turnips show 
the same amount of dry matter with a difference of manuring. 
The various swedes again differ considerably from one another, 
yet in a greater degree from the common turnips. The extreme 
variation in the entire series quoted is from 6 65 in the Norfolk- 



AgricuUural Chemistry — Turnips. 



53 



Dcscrlx)tion of Turnips. 



»i 



« 



» 



Norfolk White (lowest of experimental series) 

„ (highest of experimental series) 

4 (mean of experimental series) 

„ by farm-yard dang in experimental series 

Green common tomip, by farm-yard dang 

„ „ by superphosphate of lime 

Swede, Skirving's green top 

ft yf pmpie wop ..■ ■«■ ••• Kc. ..■ ••» 
„ paiple top (old variety, name unknown) 




Percentage 
of Dry 

Matter in 
Tuniip 
Bulbs. 



6-65 
9-30 
7-83 
7-83 
7-94 
7-94 
904 
9-61 
12-26 



whites to 12'25 in the purple-topped swede, or more than 5^ per 
cent. ; but there is little doubt that it is dependent on the variety 
of plant, rather than upon any effects of manure or culture. 

As a general inference from our results, we may state that the 
mineral and carbonaceous manures, which we have before seen to 
favour bulb-formation, — that is, to determine to an early maturity, 
are those which in a given time will yield the largest percentage 
of dry matter in the bulb ; but nitrogenous manures, on the other 
baud, which when in excess do not enhance bulb-formation (a 
process of deposition), but rather an extension of the leaf or more 
vascular system of the plant, involving a prolonged tendency to 
active circulation, and consequently a higher amount of vehicular 
watery fluid in proportion to fixed substance, will afford a smaller 
percentage of dry matter in the produced bulb. 

Were we, assuming bulb-formation to succeed leaf-formation, 
to judge from some analogy furnished by other plants, we might 
expect that the earlier organ, the leaf, would contain a less per- 
centage of dry matter than the later one, the bulb ; but inasmuch 
as the dry matter is frequently about twice as great in the former 
as in the latter, any such reasoning would imply a wrong con- 
ception of the physiological relationship of the two organs. 

We regret that the entire series of leaves of this 3rd year of 
our experiments was not collected for drying, and that indeed 
none were taken until aflier the first weighing of the crops, a few 
weeks later than the specimen-bulbs were gathered. We shall 
not, therefore, employ the results for any more important purpose 
than to show how far the efiects of manures are the same in 
kind as in the case of the bulbs, determining to the depositiruj 
or to the more circulatorij tendencies of growth. 

Here again we find no considerable variation, yet sufficient in 
amount and in uniformity to render the mean results reliable for 
our present purpose. The plants by mineral manures alone, in 
tiie first colnmn, which were the ftirthest advanced in maturation 



54 



AffricuUural Chemistry — Turnips, 



Pbbomntaoh of Dry Matter in Norfolk White Turnip Leaf. 



o 



9 
14 
18 

21 
22 



Desoription of Drilled Manniiea. 



400 lbs. calcined bone-dust, hydrochloric ) 
acid s 268 lbs. sulphuric acid ) 

11 cwts. superphosphate of lime (land \ 
trenched 18 inches deep in 1844) t 

400 lbs. calcined bone-dusty 420 lbs. sulphu- 
ric acid, 105 lbs. soda ash, 74 lbs. mag- - 
nesian limestone, and 157 lbs. pearlash , 

400 lbs. calcined bone-dust, and 400 lbs. t 
sulphuric acid ) 

11 cwts. superphosphate of lime 

Mean Results ... 



Drilled 

Manures 

only. 



dresidug of , Bape-cake 
Solph. Am. and Snlph. 
Ammonia. 



13-63 
13-93 

13-79 

13-38 
13-97 



DrIUed 
Manures, 
BAd Top- 



I>rilled 
llannrea, 
and Top- 
dressing of 



13-23 
1319 

13*48 

13-12 
13-65 



13-73 



13-31 



12-57 
12-74 

13-46 

12-68 
12-91 



12-87 



(or almost past that point), give the highest percentage of dry 
matter in the leaf as well as in the bulb. Those under the addi- 
tion of ammoniacal salt give in the leaf a percentage uniformly, 
but not so far relatively lower as in the case of the bulbs ; but it 
must be remembered that the leaves were gathered much later, 
and indeed, when, in these cases as well as in those by the purely 
mineral manures, the point of maturity and exhaustion of soil- 
supplies for organic food had been approached, or passed. We 
find again that the more vigorous plants ander both rape-cake 
and ammoniacal salt have, coincidently with the greater preva- 
lence of vascular action, a less percentage of dry matter. 

Whilst we are writing, the specimens of the present season's 
growth are being operated upon in the drying bath, but as we 
have not given any account of our experiments since 1845, we 
need only say that succeeding results indicate the same general 
facts on the subject of dry matter as those to which we have 
drawn attention. 



Having argued that, supposing the dry matter in the turnip 
were of uniform composition, a high percentage can only indi- 
cate the amount of solid substance in a given amount of produce 
at the period of growth at which the determination is mcide, and 
does not by any means unconditionally show the efficiency of the 
manures employed, we shall turn our attention to the composition 
of the dry substance itself. It has been stated that dry vegetable 
produce contains the so-called vegetable or " (nyanic " consti- 
tuents, and the " mineral " or ** viorganic" the latter being that 
portion which remains after the former is burnt away. 



Agricultural Chemistry — Turnips, 55 

We shall first speak of the composition of the organic or 
vegetable part of the turnip, and shall endeavour to show its 
dependence on the manures by which the plant is grown, and 
the probable relative feeding values of different specimens. 

We do not pretend to have reached further than the threshold 
of this inquiry, but still hope our results may furnish some 
interesting inferences. The organic matter of the turnip-bulb 
is composed of several complex bodies, some of which consist 
of carbon, hydrogen, and oxygen, whilst others contain nitrogen 
in addition to the other three elements. Other substances, such 
as sulphur and phosphorus, are also found in these compounds, 
bat in small quantities, and their presence or absence is imma- 
terial to us just now. 

Those of the compounds which contain nitrogen are in less 
proportion in plants than those in which it is absent ; but nitro- 
gen is a very important constituent in all food, so much so 
indeed that the comparative feeding value of different articles of 
produce may frequently be estimate by the amount of nitrogen 
they contain; and we shall, to some extent, act upon this 
assumption in what we are about to detail. 

Those who have read the paper on Agricultural Chemistry in 
the last number of this Journal, wiU bear in mind the remark- 
able fJGMTt there indicated, that the larger the amount of the 
nitrogen supplied by manure for the growth of wheat, the less 
was the percentage of that substance in the produced grain. 
This is not consistent with the views generally maintained on 
this subject, but it seemed to us not only sufficiently proved by 
our experiments — ^but, when it was remembered that wheat- 
grain was peculiarly a starchy seed, and that starch contains no 
nitrogen, it was thought that whatever tended to the healthy 
action of the plant (as nitrogenous manures were found to do) 
would of necessity develop the special aim and products of the 
plant, and that in fact it was more natural to expect that the 
seed woald under these circumstances be more starchy than that 
it would be more nitrogenous and less starchy. In growing 
wheair-grain^ then, by means of nitrogenous manures the per-- 
eentage of nitrogen in the produce was rather diminished than 
incr^fled. The following results will show whether a similar 
effect is observed in the growth of turnip-bulbs : — 

This is not the place to give any detailed account of our methods 
of analysis, but we may say that we.think considerable confidence 
may be placed in the results, as a comparative series ; and we 
helieve them to be, moreover, not wide of the exact truth. If we 
had to give an opinion, however, as to the probable direction and 
extent of any error, we should suspect it to be in defect rather 
than in excess, and that if it exist it is pretty uniform throughout 



56 



Agricultural Chemistry — Ttimips. 



Pebobntaoes of Nitrogen in Dry Tarnip Bulbs, the prodnce of different 

Manares. 



^lot Xombers. 1 


Description of Drilled Manures. 


DriUed 
Manures 
only. 

1-46 
1-58 


Drilled 

Manures, 

and Top- 

(Imffiing of 

Rape-oake. 


Drilled 

Manures, 

andTop- 

dreasing of 

Amzn. Salt. 


DriUcd 

Maun^ef^ 

and Top- 

drcMKing of 

Kape-oake 

nnd 
ATntn. Sftlt. 


Hi 




9 
22 


400 lbs. calcined bone-dust, hy- 
drochloric acid = 268 lbs. aid- - 
phuric acid 

11 cwts. superphosphate of lime 

Mean Kesults 


1-93 
1-89 
1-91 


2-82 
2-89 

2-86 


2-22 
2-44 




1-62 


2-33 



the series ; that its probable extent is O'lO, and its utmost range 
0*20. Should such general deficiency pervade our results, it is 
dependent partly on the fact that succulent specimens cannot be 
fully dried in air at 212® without sonie loss of nitrogen, and in 
part also upon certain practical difficulties attending the conduct 
of the determination of nitrogen in substances in which the actual 
percentage is so small as in the instances before us. We may 
add that each of the results given in this paper is the mean of 
two determinations at least, and when there has been a diflFerence 
of O'lO a third has always been made. 

Referring to the results of the table, and taking the columns 
separately, we see a very marked coincidence between the figures 
in each, and as marked a contrast between column and column ; 
and if we call to mind the peculiarities of the several organic 
conditions of manuring, we shall see the influence of the nitro- 
genous supply to be exactly opposite to that observed in the 
case of wheat-grain, and in fact that the percentage of nitrogen 
in the turnip-bulb bears a direct instead of an inverse relation to 
the predominance of that substance in the manure. 

Thus, in the instances quoted, the percentage of nitrogen in 
the dry substance of the produced bulb is by mineral manures 
alone 152 ; by the addition of rape-cake, which contains, besides 
a large amount of carbon, a considerable quantity of nitrogen, we 
have 1*91 per cent. ; by ammoniacal salts, supplying abundance 
of nitrogen, but no carbon, 2*86 per cent. ; and when to this 
exclusive nitrogenous supply rape-cake is superadded, we have 
2-33 percent. There is here seen, then, very evident connexion 
between the percentage of nitrogen in the substance of the bulb, 
and the supply of it in the manures employed. It is worthy of 
remark, however, that it is not the actual acreage quantity of 
nitrogen, but its proportion to other constituents that is so clearly 
indicated. Thus, in the third column, with an acreage supply of 



Agricultural Chemistry — Turnips. 57 

about 60 lbs. of nitrogen by manure, we have a percentage of 
2*86 io the dry matter of the produced bulb, whilst in the fourth 
column, with a supply of about 110 lbs. per acre, we have only 
2*33 per cent. ; but when we remember that in the latter case 
there was a large amount of carbon in the manure, and in the 
former none, we have a clear illustration of the close connexion 
between the provision by manure and the composition of the pro- 
duce. To render our meaning more intelligible we may further 
explain that the nitrogen in the turnip, and indeed in food- 
products generally, exists in combination with carbon, hydrogen, 
and oxygen, itself comprising nearly one-sixth part of the thus 
constituted nitrogenous compound ; the remainder of the dry 
matter consists of the compounds destitute of nitrogen, of which 
the chief constituent is carbon. Now in column 3 there was no 
carbon in the manure, but in column 4 a large amount was pro- 
vided in the rape-cake, and notwithstanding that there was in this 
case not only the same amount of nitrogen supplied by ammonia 
salt as in column 3, but further, all that of the rape-cake, raising 
the total amount to nearly double, yet the supply at the same 
time of carbon, favouring the formation of non-nitrogenous com- 
pounds, gives a less proportion of those which are nitrogenous. 

Again, if we compare the mean of these results with the mean 
percentage of dry matter under the four conditions of manuring, 
we find with the lowest percentage of nitrogen in the bulb the 
largest amount of dry matter, and with the highest percentage of 
nitrogen, the lowest amount of dry matter. There is then with 
the highest percentage of nitrogen more of circulating fluid and 
less of fixed deposited substance than with the lowest ; and since 
there was, moreover, not only a less matured bulb, but a less 
acreage produce of it in a given time than where the nitrogenous 
supply was less, we are led to infer that the high percentage 
of nitrogen indicates a relative deficiency of carbonaceous sub- 
stance, rather than a favourably increased amount of nitrogen. 
Indeed, these results will confirm the opinion already urged, 
namely, that turnip-bulb formation is very dependent on an 
abandant supply of carbonaceous matter to the roots, and that the 
more the nitrogenous condition of manuring prevails over the 
carbonaceous, the more will vascularity and the less will special 
deposition be enhanced. Thus the highly vascular seed-forming 
turnip-plant is to the less vascular bulb-forming one, as the well- 
conditioned breeding or working animal is to the stall-fed fatten- 
ing one ; a considerable amount of nitrogenous as well as car- 
bonaceous food is essential to both of these ; in the one case, 
however, exercise tends to consume what in the other increases 
tile bulk of the animal : so that whilst the food taken may indeed 
in the two cases be very similar, yet the balance of it retained in 



58 



Agricultural Chenmtry — Timiips. 



the animal will be as different as, in the cases of the two plants, 
is attained by more directly varying the supply, and the peculiar 
habits of life and growth will be developed accordingly. 

The following results further show how truly dependent is the 
composition of the turnip-bulb upon the provision by manure : — 

Fbrcentagbs of Nitrogen in the Dry Matter of Tamip Bulbs, the produce of 

different Manures. 



a 



1 
2 
3 



GonditioDS of Standaid ICanaring. 



12 tons farm-yard dung ... 

Unmanured 

8 cwts. rape-cake 



standard 

Manures 

only. 



Standard 

Manorei, 

and Top- 

dravlngof 

Bape-oake 



1-66 
3-31 
2-23 



Standazd 
Mannres, 
and Top- 
dresBlngof 
Amm.Halt^ 



217 
2-79 



2-54 

2-9^ 
2-80 



Standaid 
lfanorei» 
andTop- 
drearingof 
Rape-cake 

and 
Amm.fialt 



2-63 
300 



We see that the percentage of nitrogen by farm-yard dung is 
1*56, which differs little from either the results obtained by 
mineral manures alone, when all the organic supply was derived 
from normal sources, or from the number observed by Bous- 
singault, which was 1*70. The addition of sulphate of ammonia 
to the farm-yard dung, raises the percentage of nitrogen in the 
bulb from 1*56 to 2*54, or by two-thirds of the usually observed 
amount. Here, however, we have in the manure a large pro- 
vision of carbonaceous matter, and, as before noticed, a coinci- 
dently less percentage of nitrogen than when there was ammo- 
niacal salt alone. 

In the second line of the table we have some most interesting 
results, consistent with what have gone before, and, further, 
affording a new and significant illustration of the office of the 
turnip as dk fallow-crop. 

It will be recollected that the average weight of the bulbs on 
the unmanured plot was, in this season of 1845, less than 2 oz., 
and that the entire produce was only 13^ cwts. per acre. We 
find, however, that these stunted bulbs give a percentage of 
nitrogen higher than any in our series, even than those which had 
an unusually excessive supply by manure, and twice as high as 
the amount supposed generally to exist in the cultivated bulb. 
We may reasonably infer that, under the influence* of season and 
a soil reduced to the lowest conceivable state of exhaustion, as 
regards its fitness for the growth of the cultivated turnip, the 
natural supply of nitrogen was, in proportion to that of other con- 
stituents, abundantly available to the special accumulative powers 
of the plant. In the same line we find, in the second column, 



Agricultural Chemistry — Turnips. 59 

that the snpply of a top-dressing of rape-cake to this otherwise 
exhausted plot, raises the acreage produce of bulb from 13^ cwts. 
to 7^ tons, and the average weight of bulb from less than 2 to 
nearly 11 oz., and notwithstanding the nitrogenous supply of the 
rape-cake, we have, with its large provision of carbonaceous sub- 
stance, the percentage of nitrogen reduced £rom 3*31 to 2*17. 
In the 3rd column, where there is added to the natural supplies 
of £oil and season nitrogen, but no carbon, we had an evidently 
unhealthy condition ; for the acreage produce, the size of bulb, 
and the number of plants, were all less than where there was no 
manure whatever. Again, with these unfavourable circumstances 
of growth we have a very large percentage of nitrogen ; less, in- 
deed, than in the unmannred ' bulbs, but considerably higher 
than when rape-cake alone was used. In the 4th column we 
have the same supply by manure of carbon and nitrogen as in 
column 2, with the addition, however, of the nitrogen as in 
column 3, and we find, as in other cases, that although the 
actual supply of nitrogen is greater than in column 3, it being 
proportionably less, the percentage in the bulb is reduced. 

In the third line the standard manure is rape-cake, the extra 
dressings being, as usual, a further addition of rape-cake, of am- 
moniacal salt, or of both. Comparing the percentage of nitrogen 
by the drilled rape-cake, as in colunm 1, with that by farm-yard 
dung, we find that the rape-cake gives the highest, and we would 
suppose the proportion of nitrogen to carbon would be greater. 
In column 2 the amount of rape-cake being greater, the per- 
centage of nitrogen is greater : the svjpply of nitrogen to that of 
carbon is not, however, greater than in column 1 ; but we have 
before seen that a full quantity of rape-cake, without extra 
mineral manure, is not conducive to the most healthy growth of 
the turnip-bulb ; nor indeed would the carbon so supplied be so 
completely and rapidly available as the nitrogen. The addition 
of ammoniacal salt, in column 3, raises the percentage of 
nitrogen from 2*23 to 2*80, and in column 4, as compared with 
column 2, from 2*79 to 3*00. 

We have made other determinations of nitrogen in turnip- 
bulb, with a view to some more special points, but as we cannot 
discuss them in this paper without extending our remarks to an 
undue length, we shall defer notice of them until a future 
occasion. The results already given are, moreover, we think, 
sufficient to aid our estimation of the characters of the turnip 
>8 a food and rotation crop. 

An important fact elicited is, that within a certain range, which 
indeed is wider than has generally been supposed, the organic 
composition of the turnip bears a very direct relation to that of 
the manures by which it is grown. It is seen that the proportion 



60 



Agricultural Gliemistry — Turnips, 



of nitrogen usually found in the cultivated turnip-bulb may be 
nearly doubled by means of ammoniacal manures, and since we 
have stated that the feeding value of a crop may to some extent 
be measured by its percentage of nitrogen, it might be supposed 
that we should be led strongly to advocate the use of such man- 
ures in the growth of the turnip. Our field experiments have 
already shown, however, that this would be a one-sided inference 
from these departmental results ; and when we come to make 
fiome general application of our varied evidence to practical and 
economic agriculture, the true position and bearing of the dif- 
ferent branches of the question will be indicated. 

We regret that we have not as yet a sufficient number of 
determinations of nitrogen in the turnip leaf to enable us to 
decide satisfactorily whether the percentage be as clearly de- 
pendent upon the supply by manure as in the case of the bulb ; 
the vigorous leaf being, however, highly vascular, and containing 
much of the still circulating unassimilated food derived from the 
soil, we might anticipate it would be so ; but on the other hand, 
if we look at the bulb as a reservoir of matters which are in 
excess so far as the natural seed-fonning tendencies are con- 
cerned, we might expect the less artificial organs, the leaves, 
would be more constant in their composition. The following 
results will not assist us much in deciding these questions ; they 
are, however, not without interest : — 

Febcentaob of Nitrogen in the Dry Matter of Norfolk White Turnip Leaf. 





i 




1 


Specimen 




1 

g 




1 Dried 


dried below 
300°, and < 




1 


Description of MannreK. 


, at 


Nitrogen cal-' 




^ 




212°. 


ciliated upon 




t 






folly dried 1 




fi^ 






Substance. 




1 


Farm -yard dung ... 


3-24 


3-60 i 




2 


Unmanured 


4-22 


4-35 



Here are given the results obtained from specimens of leaf, in 
one instance dried fully at 212^ in the water bath, and in another 
dried much below that temperature ; the percentage of nitrogen 
in this*Case being calculated upon the fully desiccated substance. 
The fact before alluded to, that succulent specimens frequently 
lose nitrogen at 212^, is thus illustrated ; in one instance there 
is a defect of 0'36, and in the other of 0*13. We have met with 
a similar result with other succulent substances. 

It will be remembered that the turnip-leaf was found to contain 
a proportion of dry matter more than half as large again as the 
bulb ; and it is seen that in the case of the dung specimen the dry 



AgricuUural Chemistry — Turnipi. 61 

matter of tfie leaf has a percentage of nitrogen twice as high as 
that of the bnlb. A given weight of the fresh leaf would there- 
fore contain more than three times as much nitrogen as an equal 
amount of bulb. Since, however, the bulk of the leaves at the 
time the turnip crop is gathered or consumed are past the condi- 
tion in which our picked specimens were taken for analysis, it 
would be unsafe to employ these results for purposes of acreage 
calculation ; yet they are in other respects to be relied upon. 

Comparing the characters of the cultivated with those of the 
uncultivated plants, as shown by the analyses which have been 
given, we observe the decrease by cultivation in the percentage of 
nitrogen in the dry matter is in the leaf only '75, but in the bulb 
1*75 ; from which, again, we may perhaps gather that the cul- 
tivated bulb is the result of a continued accumulation of secreted 
matters, formed in quantity beyond the essential requirements of 
the plant as such : the leaf, on the other hand, containing, besides 
its own special structures and products, little more than those sub- 
stances derived from immediate supply, — has, therefore, a com- 
position in a less degree varying according to the constant 
circomstanoes of growth, but comprising a larger proportion of 
unsecreted matter. 

The fact that, notwithstanding the large nitrogenous contents of 
turnip-leaves, they should only be to a small extent valued as food, 
doubtless arises from the large amount of matters which they con- 
tain only brought within the range of the organism, themselves as 
yet unorganised, and existing as saline and other changeable 
fluids, to which we may readily attribute a medicinal and purga- 
tive, rather than a direct nutritive effect ; elaboration to some 
extent being, as we are aware, an important element in the con- 
dition of food for animals. The low degree of stability in some 
of the nitrogenous contents of succulent substances, as indicated in 
the drying process, as well as our conceptions of the offices and 
physiological position of the different parts of a plant, bespeak, 
indeed, that where an active circulation is still proceeding, there 
will be found not only the actual and fixed but also the prospec- 
tively possible constituents, the latter as yet only in a vehicular 
condition, and little influenced by the selective and appropriate 
powers of the organism. It is true that the varying character of 
the vital apparatus of different animals adapts them to the use of 
vegetable food in varying degrees and states of elaboration ; but 
there s«ems to be a point in this degree of elaboration below 
which constituents lose their food-qualities ; or even, it may be 
doubted whether, in such cases, the matters are not really as little 
truly vegetable as would be the watery extract of the soil as it is 
taken up by the rootlets, and from the condition of which little 
deviation has hitherto resulted from the vital actions of the plant. 



62 Agricultural Chemistry — Turnips, 

Such substances, indeed, may perhaps be considered as still be- 
longing to the mineral kingdom, upon which animal life cannot 
be sustained. 

Referring to the more special lesson of the experimental results 
last given, we notice, that whilst the leaf grown by &rni-yard 
dung contains 3*60 per cent, of nitrogen in its dry matter, that 
grown without manure of any kind in a turnip-bulb exhausted 
soil has 4'35 per cent. ; and it will be remembered the bulbs cor- 
responding to these specimens of leaf give respectively 1*56 and 
3'31 per cent. We have, then, in the leaf as well as in the bulb, 
a larger proportion of nitrogen in the more natural but agricul- 
turally useless turnip than in the cultivated one ; and if we are 
right in considering that, within certain limits, the composition of 
a succulent imperfectly elaborated vegetable will bear some direct 
relation to the supplies of food within its reach, we must conceive 
that there was, independently of art, a resource of nitrogen avail- 
able to the uncultivated plants far beyond that of other necessary 
constituents. If, then, the powers of reliance upon normal sup- 
plies of nitrogen here observed are to be fully developed and 
turned to economical account, it is more especially by means of 
an artificial provision of the other constituents that this object 
will be attained. 

We think that in these facts we have a beautiful illustration of 
some of the physical and physiological characters upon which 
depend, materially at least, the economic value of the turnip in 
rotation with com. The true econowy of alternate cropping, 
whilst, however, it is intimately associated with functional differ- 
ences, such as we have shown to exist in the selected plants, yet 
depends much also upon the destination and uses of the produce, 
independently of which, the peculiar accumulative tendencies of 
the different crops could not be rendered profitably subservient. 
We shall not, however, consider the connexion between the 
various sources of the economy of a rotation of crops, until, hav- 
ing detailed all the evidence which it is our intention to bring 
forward, we come to sum up and apply our departmental results 
to the practice of agriculture. 

We shall now give some account of the mineral substances 
found in the turnip. Our experimental results referring to this 
branch of the question are very numerous, and it was our wish to 
have considered them somewhat fully ; but as our permitted space 
is already nearly exhausted, we must defer doing so until a future 
opportunity, and confine our remarks on this occasion to some 
explanation of the nature of the subject, and to indicating the 
general bearing of our evidence upon the conclusions which have 
been arrived at in the foregoing pages. 



Agricultural Ghemistry — Turnips. 63 

The knowledge which we at present possess of the amount, the 
composition, and the office of the mineral matter found in com- 
hmation with the various definite orgeoiic compounds of which the 
solid and fixed substance of a plant is made up, is very limited ; yet 
it is such as by no means leads us to assign to all the constituents 
of the ash of a crude vegetable product an essential position in 
the constitution either of the parts already elaborated, or of those 
which would result from the continued growth of the plant. It is 
obvious that an examination into the nature and constancy of the 
circumstances of growth, with which variations in the quantity and 
composition of plant-ashes are connected, cannot alone provide an 
explanation of the uses and importance of the mineral substances 
in the plant ; it is, however, an essential step in the inquiry, and 
the results attained by it must materially direct and aid any 
collateral course of investigation. 

In entering at once upon this part of our evidence, we may 
again state that we did not determine the amount of dry matter in 
the produce of the first two seasons' experiments ; we are unable, 
therefore, to give the percentage of ash in the dry matter in the 
specimens of those two seasons, and it will afterwards be seen that 
this particular is more significant than that of the percentage in 
the fresh produce. On this account, and as we wish to compress 
onr matter as much as possible, we shall not give any statement 
of the results of those two years, but only remark that a close 
examination of them affords like conclusions to those to which 
the third season's experiments lead us. 

The percentage of ash in the fresh bulbs, the mean of the pro- 
duce of each of the four conditions of manuring, frequently 
referred to before, are given below. 



G«iiefal Desoriptlon of Uannrlng. 



Seaaon 1 845. — Mean of 13 ezperiments by purely mineral manures 
Season 1846. — Mean of 13 ezperiments by mineral manures and 1 

rape"Caj£6 suqgcl ••• ••« ••• ••• >•• ••• ... j 

Season 1845. — Mean of 13 ezperiments by mineral mannres and 1 

ammoniacal salt / 

Bnwtt 1845. — Mean of 13 ezperiments by mineral manures, and \ 

both ammoniacal salt and rape-cake J 



Percentage 
of Ash in 
Fresh Sub- 
stance of 
" Norfolk 
White*' 
Turnip Bulb. 



0-58 
0-57 

0-61 

0-60 



These results are the actually found percentages of ash, without 
any deduction for adventitious substances, such as siliceous 
laatterand charcoal. The figures exhibit very slight differences, 
such as could not justify any important conclusions, were these 



64 



Agricultural Chemistry — Turnips, 



contrary to otherwise probable indications; we find, however, 
that, slight as the differences are, they are such in kind as other 
circumstances would lead us to anticipate; and we need only 
notice that the percentage of ash is seen to be highest where the 
nitrogenous condition of manuring was predominant, and lowest 
where the carbonaceous was more characteristic. 

The variations are, however, more apparent when the percent- 
ages of ash upon the dry, rather than upon the fresh, matter 
are given. The mean percentage of the dry matter itself, and 
of its ash, in the specimens last quoted, and of the nitrogen in 
the dry matter of two of the specimens in each case, are here 
tabulated : — 



General Description of Manuring. 



1 845. — Mean of 13 experiments by purely mineral 

UUcUIUa w9 ■•■ ••• ••• ••• •■• ••• ••• 

1845. — Mean of 13 experiments by mineral' 
manures and rape-cake 

1845. — Mean of 13 experiments by mineral ) 
manures and ammoniacal salt ) 

1845. — Mean of 13 experiments by mineral man- 1 
ures and ammoniacal salt and rape-cake j 



Percentage 
of Dry 

Matter in 
Bulb. 



8-34 

7-41 

7-48 



Percentage 
of Ash in 



Peroentage 
of Nitrogen 
Id Dry 
jj Matter 

MatSr. ^SP«^?*?f 
• Nob. 9 and 

2S). 



6-99 
7-21 

8-24 
808 



1*52 
1-91 
2-86 
2*33 



The coincidences here brought to view are of considerable 
interest, and clearly show a constant decrease in amount of mineral 
matter as the deposition of solid vegetable substance progresses. 
We have with the highest proportion of dry, the lowest proportion 
of mineral matter ; and with the lowest amount of dry matter, the 
highest of mineral substances ; and even with the slight increase 
in dry matter exhibited in line 4, compared with line 3, we have 
a decrease in the percentage of mineral constituents. We can 
scarcely fail to recognise .in these results a marked distinction 
between those constituents of the bulb which are as yet merely 
circulatory and unappropriated, and those which are secreted and 
fixed, the former being indicated by a small amount of dry matter 
and large amount of ash, and the latter by a large amount of dry 
matter and a small amount of ash. 

The connexion between the amount of diy matter and its per- 
centage of ash being admitted, and that between the amount of 
nitrogen, that of dry matter, and the condition of maturation 
having been pointed out before, it is seen that the views taken 
are fully confirmed by the relation of the ash in the dry matter to 
that of the nitrogen in the same. Thus we have in the Table, 
with the most fixed matter and least nitrogen, also the least ash ; 



AgricuUiural Ohemieiry — Turnips, 



65 



and with the most ash and most nitrogen, the least dry matter. 
The rehitive tendency to bulbons deposition, or active vascular 
ditmlation, under carbonaceous and nitrogenous manures respeo- 
tively, is here again exhibited. 

It will be remembered that the specimens of turnip-leaf which 
were examined, were gathered very late in the season — ^the few 
that could be selected green being taken. All were, however, 
far advanced in stage of growth, and it was found that, whether 
owing to an uniformity in the stage of growth, or to the essential 
tendency of the leaves, as different from that of the bulb, there 
was very Uttle variation in the proportion of dry matter, compared 
with that observed in the bulbs. The following mean results will 
illustrate this : — 



RcteroDoe to mstory of the Speoimens. 


Peroentage 

of Dry 

Matter in 

Leaf. 


Feroentaflre 

of ABh 

in Fresh 

Leaf. 


Percental 
of Ash In 

Dry 
Matter. 


Mean of 9, 14, 18, 21, and 22, with mineral 1 

Mean of 9, 14, 18, 21, and 22, with mineral 1 
manures and ammoniacal salt j 

Mean of 9, 14, 18,21, and 22, with mineral \ 
manues, rape-cake,and ammoniacal salt J 


18-73 
13-31 
12-87 


1-31 
1-26 
1-25 


9-52 
9-49 
9-72 



The differences here seen are, as we have already implied, 
small ; nor are the results so undoubted in their bearing as most 
that have been quoted ; yet still we have with the smallest amount 
of dry matter, ^e largest percentage of ash in the dry matter. 
The centre column shows the lowest percentage of ash in the 
fresh leaf in this case ; but it is of course the percentage to water, 
rather than to dry vegetable substance, that is there indicated. 

The comparative ash results that have been given, whether of 
the tumip>bulb or leaf, lead us then yet again to draw some distinc- 
tions between the fixed and the circulating constituents of a suc- 
culent plant, and to trace the proportion of these respectively to 
the stage of maturity of the organ, whilst this has been found to 
depend greatly upon the supply by manure. 

Were we to compare the composition of the leaf, as thus far 
flhown, with that of the bulb, and to attempt to apply on all points 
the same kind of reasoning as between bulb and bulb, or leaf and 
leaf, we should at once meet with inconsistencies, for we find in 
the earlier product of the plant — the leaf — a much larger amount 
of dry matter than in the later one — ^the bulb. And again, with 
the higher percentage of dry matter in the leaf, we have at the 
same time a much larger amount of ash in that dry matter. Such 
comparisons are, however, physiologically, quite inadmissible. 
Looking at the question in another view, however, we have attri- 

F 



66 Agricultural Chemistry — Turnips. 

bated to the bulb, notwithstanding its large amount of water, in 
some respects a higher condition of elaboration, or fixedness in 
its solid constituents, than to the leaf. We have, indeed, supposed 
that bulb formation, in the degree in which it is developed for 
feeding purposes, is a deposition of matter existing in quantity 
beyond what is essential to the health of the natural plant, much 
as depositions are known to take place in animals under some- 
what analogous circumstances. 

The following comparative statement of the proportion of ash 
in the dry matter of the leaf, the bulb, and the seed of the Norfolk 
White turnip, will favour the view that the composition of the bulb 
implies a more advanced selective process than that of leaf: — 





Leaf. 


Bnlb. 


Seed. 


Percentage of ash in the diy matter of 


9-5 


6-9 


4-5 



There is then, comparing one organ with another, as well as 
different specimens of the same organ, a diminution in the pro- 
portion of the mineral to the organic constituents of the plant the 
farther we advance towards the matured results of the vital process. 
It is true that even in the seed the amount of mineral substances 
is greater than our conceptions regarding the composition of the 
definite compounds of which it is made up would alone have led 
us to anticipate ; but numerous experiments with wheat grain 
show that, however small may be the differences exhibited in a 
series of specimens which can be compared with each other in this 
respect, yet they will indicate the less percentage of ash in the 
dry matter the higher the percentage of the diy matter itself — 
that is to say, the more completely ripening processes have been 
developed. An excess of mineral matter in any such case may to 
some extent therefore be owing to an increased proportion of 
vascular contents to perfectly elaborated substance. 

Admitting that the mineral substances found in the leaves of 
the turnip and of other plants are such in variety and in amount 
that we cannot suppose them to be all destined to enter into com- 
bination, and actually to constitute a portion of the fixed and 
essential formations of the plants, yet their presence within it is 
not on that account quite inexplicable. The experiments of De 
Saussure and others show that the rootlets of a plant take up the 
dissolved substances presented to them, exercising but little of 
selective power, whilst such as they have is rather of a mechanical 
than of a more purely vital kind. It is not to be wondered at, 
then, that the composition of the ash of highly vascular vegetable 
substances should exhibit a wide range of difference, according to 
climate, manuring, and soil. In such cases a large proportion of 



Agricultural Chemistry — Turnips. 



67 



the mineral matters are distributed, not as constituents of the 
oiganised substance of the plant, bat in its vessels and flaids, 
owing their quantity and character, to a great extent, to the 
external influences just referred to, but little, comparatively, to 
the selective processes of the organism. 

The following mean results of analysis seem to show that the 
more the truly vital processes have been exercised, the more 
special does the composition of the mineral matter become : — 



Potass 

Chloride of potassiam 
cyOGa ■•• •■• 
Chloride of sodium 

liime 

Magnesia ... . 
Phosphoric acid * 
Snlphnric acid 
Carbonic acid 



Leaf Aslu 



]£caD of S4 

Analyses by 

Mr. D. 

CampbelL 



2205 
4-84 
019 
616 

30-63 
0-82 
605 

12-55 

17-82 

100-00 



Bulb Ash. 



Mean of 34 
Analyses by 
Dr. Gilbert. 



44-84 
0-34 
1-79 
6-86 

11-40 
1-46 
7-89 

10-63 

14-79 



100-00 



These results being the mean of so many analyses as twenty-four 
in each case, the general character of the distinctions they exhibit 
may be fully relied upon. It is to be regretted that we have not 
an actual analysis of the ash of the seed of the Norfolk White, to 
place by the side of those of the leaf and of the bulb. We know, 
however, that phosphoric acid, potass, and magnesia are eminently 
seed-ash constituents, and that the existence of the vehicular 
element, chlorine, in a perfectly ripened seed is doubtful. The 
increase in the percentage of the more special, and decrease in 
that of the less special constituents, is clearly shown in the results 
given above, as we proceed from the earlier formation to the later 
one, the composition of which is more influenced by the peculiar 
elaborative action of the organism. Of the soda salts, indeed, 
the actual amount is somewhat larger in the bulb than in the 
leaf, but their proportion to the potass ones is much less. 

It has been observed that the ash analyses of green crops seem 
to afford confirmation of the much discussed theory of the substi- 
tution of potass by soda in plants, but that those of grain crops, 
on the other hand, do not serve the same purpose. It seems to 
08, however, that if in green and succulent substances, in which 

* In the analysis of the leaf and bolb ash, the phosphoric acid is calculated 
from the bone-earth precipitate, taking no account of the small quantity of 
inm salt usually present. 

v2 



68 Agricultural Clt&inistry — Tuniips, 

there exists a considerable amount of matter admitted by the 
roots, with but little of special selective power, the proportions o! 
potass and soda may vary according to the variations in the soluble 
contents of the soil, but the further we advance towards the nlti- 
mate results of the organism, the larger is the proportion of potass 
to soda ; there is in such a fact evidence against the supposition 
that the vegetable organism can substitute the one alkali for the 
other, for in the case assumed soda would seem to be present 
only hefopre the viial selective processes had been exercised upon 
the matters brought within their sphere of influence. If, then, 
the theory refeired to suppose a replacement of potass by soda, 
as an actual constituent of vegetable products, we think that facts 
hitherto observed are such as should tend to disprove rather than 
to prove its validity. On the other hand, we may weU believe 
that the large amount of mineral matters admitted into a plant, 
beyond that which is likely to become fixed and combined with 
its structures or deposits, has, nevertheless, some office to perform. 
We know too little, however, of the means employed by the vital 
processes to enable us to assign special agencies to special sub- 
stances ; yet the presence of mineral matters not actually to take 
part as constituents, is by no means improbably of essential im- 
portance in determining the changes to which the circulating j uices 
of the plant are subject; nor is it impossible that in such an office 
as this soda may substitute potass, and one acid another, that is 
to say, as ag&nts, if not as constituents. It is, indeed, only by sup- 
posing some other requirement in the plant than that of mere pro- 
vision of actual constituents, that we can in any degree account, 
either for the extraordinary effects which a large supply of 
mineral substances is in some cases found to produce, or for its 
possession of the power by virtue of which so large an amount of 
such substances is taken up by its roots and distributed through- 
out its living organs. 



It was our intention to bring forward many more results, both of 
the field and laboratory, relating to the important subject of root- 
culture, had our space permitted it. We have still eighty analyses 
of ashes obtained from turnips, the history of the growth of which 
is detailed in this paper. It would also have been advantageous 
to give, in less technical language, a short summary of the results 
arrived at in the course of these experiments, for the convenience 
of those re€Mlers who are more conversant with practical than with 
scientific agriculture. Having, however, through the kindness of 
the Journal Committee, already extended our article to a length 
beyond what is usually allotted to contributors; we must conclude 
with a brief explanation of the uieatis to he employed in the pro- 



Agricultural Clteinistry — Turnips. 69 

fitable coltiratdon of roots, and of the peculiar properties which 
they possess, and which constitute their value as fs^low-crops. 

A practical fanner, accustomed to consume his turnips upon his 
land every fourth or fifth year, might be inclined to doubt the 
correctness of any conclusions drawn from a set of experiments so 
artificial as the removal of five successive crops of turnips from 
the same field. It should, therefore, be distinctly understood that 
the object of these experiments is not to provide any examples 
for direct imitation in practice, but to enable us to ascertain the 
real characters of season, soil, and manuring required for the 
growth of the turnip, in order that, the principles of its culture 
being better understood, the practice of it may be more econo- 
mically carried out. 

In our experiments upon wheat, given in the last number of 
this Journal, we showed that the produce of grain, beyond that 
which the soil and season gave in successive years, was de- 
pendent upon the supply of nitrogen ; that 100 lbs. of rape-cake, 
containing 5 lbs. of nitrogen and 80 to 90 lbs. of carbonaceous 
matter, gave no greater increase of com than a salt of ammonia 
containing 5 lbs. of nitrogen and no carbonaceous matter ; and 
that the produce from 14 tons of farm-yard dung upon the same 
space of ground year after year was invariably less than that 
which was obtained from 2 cwts. of ammoniacal salts. The farm- 
yard dung and rape-cake increased the produC/e of grain in pro- 
portion to the amount of nitrogen which they contfianed ; but as 
the rape-cake contains only 5 per cent, of nitrogen, and dung, 
frequently not a ^ per cent., or one pound in 200, to what pur- 
pose can this bulk of carbonaceous matter be applied ? As long 
as com is cultivated, it is evidently of little use. 

Our experiments upon turnips answer this question in a most 
satisfactoiy manner. They show distinctly that the produc- 
tion of turnip-bulb depends upon the supply of carbonaceous 
matter in the soil, and that the tme office of the turnip and 
other root-crops consists in converting the otherwise useless 
refuse of our corn-crops (straw) into a succulent and nourish- 
ing food for animals. During the five years over which our 
turnip experiments have been carried, in only one instance 
has the acreage weight of bulbs reached 17 tons. We know 
that the mineral matter required by the turnip has not been 
deficient, and in many instances very large quantities of nitrogen 
have been supplied ; but the essential substance, carbonaceous 
matter, required for bulb-formation, has been but moderately 
supplied in the form of rape-cake ; in one instance, where it was 
supplied in a larger quantity by dung, the greatest produce was 
obtained. Having, therefore, shown that to obtain heavy crops of 
bulbs, large amounts of carbonaceoutf matters should be supplied 



J 



70 Agricultural Chemistry — Turnips. 

to the soil, and that dung is the cheapest source of this substance, 
the question next arises, What are the best substitutes for it ? 

Dung is an article in which our farm-yards are very apt to be 
deficient. It might be supposed that if sufficient carbonaceous 
matter were once accumulated upon a farm exporting only com 
and meat, the loss in these two products would not be greater 
than would be supplied in return by the atmosphere ; but the ex- 
periments of Boussingault and Dr. R. D. Thomson show that 
the amount of such matter respired by an animal, and therefore 
lost to a farm, is very great ; indeed we should not be far wrong 
if we said that in feeding a crop of turnips by stock one-half of the 
carbonaceous matter in it is lost to the farm. To restore the loss 
of organic matter most economically, various processes are recom- 
mended : some advocate the consumption of artificial food with the 
turnip ; some the employment of ammoniacal manures in order 
to collect carbon from the atmosphere ; and some maintain that 
if the mineral substances composing the ash of the turnip were 
restored to the soil, it could supply itself with organic matter. 

To commence with the mineral manures : — Analysis has shown 
that a great portion of the ash of the turnip consists of the 
alkalies, potass and soda, and of magnesia — and these substances 
have been recommended in the formation of mineral manures ; 
we think, however, that a careful examination of the position 
which the turnip-crop holds in a rotation, and the manner in 
which its organic and inorganic matters are applied in farm 
practice, will show that the artificial supply of alkalies can 
rarely, if ever, be advocated. A fair crop of turnips would 
contain in leaf and bulb about one ton and a-half of dry matter, 
of which 250 lbs. would consist of minerals. Omitting those 
minerals which are of less importance to consider here, we may 
take the composition of the crop as follows : — 

Dry organic matter 3110 

X wUUSU ••* ■•■ ••• •••  ••• ••• ••« Xwt 

Phosphate of lime 50 

Sulphate of lime 40 

Of the organic matter, more than one-half of the carbon, but 
probably scarcely one-fourth of the nitrogen, is lost to the farm 
by the respiration and increase of the stock.* The amount of 
phosphate of lime removed would vary greatly with the nature 
of the stock consuming the turnips. A breeding flock or young 
growing animals abstract large quantities to be employed in the 
production of bone, while full-grown animals require very much 
less. Of the alkalies contained in the ash of the turnip the 
stock return to the soil nearly all they take up. Barley generally 

* This retention vjfon the farm ^ of nitrogen Bpecially^ demands more notice 
than our spaoe permits. 



. Agrieultural Chemistry — Turnips. 7 1 

follows after turnips, the greater part of the com being taken to 
market. A crop of 40 bushels carries off phosphoric acid equal 
to about 28 lbs. of phosphate of lime, and 9 lbs. of potash. The 
clover following the barley, being consumed by stock, causes a 
farther loss to the farm of organic matter and phosphate of lime, 
bat of little or no alkalies ; while the wheat grain removes about 
12 lbs. of potash and 30 lbs. of phosphates. 

We see, therefore, that much of the organic matter of the 
turnip is lost to the farm by respiration, and the phosphate 
of lime largely in the formation of bone ; while the export of 
potash is so small that the quantity contained in one acre of 
tumipfl would not be entirely exported under twenty years. It 
is clear, then, that unless by actual waste, there is, under an 
ordinary course of farming, without the use of imported food, a 
comparatively small decrease in the amount of available alkalies 
m the soil ; but when we consider the vast amount of alkalies 
existing in the soil itself, and set free by annual decomposition, 
and that in every well-cultivated farm there will be a consider- 
able quantity imported in cattle food, there can be little doubt 
that, under ordinary circumstances, the available alkalies accu- 
mulate in the soil. It may be further remarked, that in our 
experiments the alkalies, in whatever form we applied them, 
were always injurious to the vigorous growth of the young plant. 
Although the export of phosphate of lime &om a farm is very 
much larger than that of the alkalies, the continual use of it 
as a manure for the turnip-crop could not be advocated upon 
the ground of mere exhaustion ; for it could be proved that 
where the supply of it to the turnip-crop during successive years 
has been much greater than what has been removed in produce, 
the effects of further applications were equally successful. 

We are therefore inclined to limit the economical application 
of mineral manures to phosphate of lime alone, and even then in 
most cases it is employed, not as an element of which the soil 
generally is deficient, but as an agent for promoting to a remark- 
able degree the early and vigorous development of the young 
plant within a limited range, and carrying it with rapidity over 
those stages, any delay in which is attended with great injury, 
and often with the destruction of the whole crop. 

The sources of phosphate of lime are guano, bones, and the 
compound of phosphates and sulphuric acid, called superphos- 
phate of lime. The latter manure is the form which is found 
to produce the greatest effect upon the young plant, and espe- 
cially upon the development of a large amount of fibrous roots. 
AlthDugh strongly acid, it may be drilled with the seed without 
the slightest injury to it. 

It must, however, be clearly understood that the bulk of an 



72 AgriciiUural Chemistry — Turnips, 

agricultural crop of turnips depends materially upon the amount 
of organic matter contained in the soil, without which the deve- 
lopment of the power of growth by means of the phosphate 
will be unavailing. The first application of a mineral phos- 
phate is liable to produce heavier crops of turnips than those 
which follow, unless the carbonaceous matter taken from the 
soil by the turnips, and lost by the respiration of the stock con- 
suming them, has been made up by imported cattle food. Bape- 
cake, as containing a large amount of organic matter, is an 
admirable manure for the turnip as a substitute for farm-yard 
dung ; it may be employed in conjunction with superphosphate 
of lime — ^the former being sown broadcast, and the latter drilled 
with the seed. 

Peruvian guano, whidi contains a large quantity of am- 
monia as well as phosphates, is found to be a much more certain 
manure for turtiips in Scotland, where the fall of rain is large, 
than in those parts of England where it is much less. Indeed, 
the natural agencies of season are much more favourable to the 
growth of turnips in Scotland and the north and west of England 
than in the eastern counties, where the application of skill and 
capital, upon a soil well suited to the plant, has gained for them 
a high reputation. In the south of England, and wherever the 
comparatively small amount of rain that falls renders the pro- 
duction of the turnip-crop uncertain, the cultivation of the 
mangold-wurzel might be extended with considerable advantage : 
it can be sown sufficiently early in the spring to enable it to 
extend its roots deep in the soil before the dry weather sets in, 
it is not liable to injury from insects, and it is capable of pro- 
ducing a larger amount of solid food than any other crop in a 
rotation. The objection raised against it as an exhausting crop 
arises partly from the small amount of produce which it yields 
from a given weight of manure compared with turnips ; but as 
the percentage of dry matter is greater, the objection may not 
be valid. The following table shows the amount of dry matter 
contained in various root-crops grown this season upon Rotham- 
sted Farm under ordinary cultivation : — 

Percentage of dry matter in Long Bed Mangold-wurzel ... 12*7 

Yellow Globe „ ii-34 

Common Swede (name unknown) 12-8 

Skirving*8 Swede, purple top ... 9*4 

.♦ » green top ... 9-4 

Green common Turnip 7«9 

Norfolk White 7g3 



»» l» 

»♦ »» 

»» tr ft n 

»» ♦» 

tl It 



We see by this table that 10 tons of mangold-wurzel contain as 
much dry matter as 15 tons of white turnips, and that the dif- 
ference in bulk between a crop of Skirving^s, compared with one 



J 



Agricultural Chemistry — Turnips, 73 

of the older sorts of swedes, is due to the difference in the pro-' 
portion of the water. That the soil on this farm, although not a 
turnip soil, is capable of producing good root-crops, under a proper 
tupply ofmanurSy may be inferred from the fact that this year, 
which is anything but a good turnip season, an acre of swedes 
was weighed, the bulbs of which gave 20 tons 10 cwts. ; number 
of plants per acre, 20,120 ; average weight, 2 lbs. 3 oz. Ten of 
the largest were found to weigh 112 lbs. 

We found in our experiments that the usual percentage of 
nitrogen could be nearly doubled by the use of ammoniacal 
manures ; but we do not recommend the general direct use of 
snch manures for turnips, notwithstanding that the value of our 
produce as food depends much upon the percentage of nitrogen 
it contains. 

On some future occasion we shall endeavour to show that, 
excepting rape-cake, the manures in the market containing nitro- 
gen are more advantageously employed for clover, and other 
crops of the like kind, than in any other place in the rotation. 

If a proper quantity of imported food be consumed upon a 
farm, the direct supply of nitrogen to the turnip crop by means 
of artificial manures will certainly not be necessary. An excess 
of nitrogen in the soil produces too large a proportion of leaf, and 
too little tendency to form bulb. It is true that a crop of turnips 
baring a large proportion of leaf will give a larger amount of 
manure to the land ; but its yield of food will be comparatively 
small. But, since the manure obtained in such a case previously 
rasted in the soil, the economy of the crop, even so far as its 
manuring influence is concerned may be doubted. In fact, so 
&r as our experiments upon this subject enable us to judge, we 
believe that where the supply of nitrogen to the soil is very great, 
the amount of it collected from the atmosphere is less, and thus a 
part of the benefit of the crop would be lost. All the specimens 
in which we found a high percentage of nitrogen were those in 
which there was a great development of leaf with a compara- 
tively small tendency to form bulb ; and we believe that the high 
percentage was due to a deGcient accumulation of carbon by the 
plant. Whilst, then, a high percentage of nitrogen may indicate 
an abundance of it in the soil, the growth of the plant has been 
in other respects defective. It is probable that the full-grown 
bulb of such a plant as has only a due proportion of leaf will sel- 
dom have a percentage of nitrogen much higher than that which 
has been usually observed ; for with an increased supply of nitro- 
gen there is an excessive production of leaf, and a bulb which, 
though richer in nitrogen, is not profitably developed. There is, 
however, a casual advantage in having a somewhat full supply of 
nitrogen in the soil for those of our turnips which are to be eaten 

o 



74 AgricuUniral Chemistry — Turnips, 

late in the season ; for the plants so grown, whilst they may hare 
a less favourable proportion of bulb, yet, owing to the increased 
vitality and hardiness which result from the nitrogenous manure, 
the bulb is better fitted to stand the winter temperature without 
injury. A sufficient importetion of food for stock will^ howeyer, 
render the purchase of nitrogenous manures for the turnip crop 
quite unnecessary ; but where such manures are employed, rape- 
cake will be found to ' afford a sufficient, and in oUier respects 
the most advantageous, means of supply. 

Lastly, it must not be forgotten that the tillage of the soil con- 
stitutes a most essential element in turnip culture ; and that he 
who sows his turnip-seed upon a badly-cultivated soil is only 
throwing away his time and money. The naturally Ijght and 
porous nature of a turnip soil points out what are the require- 
ments of these plants ; and when the necessary degree of tilth has 
been obtained, and the seed sown, the introduction of air beneath 
the surface of the soil by means of the horse and hand-hoe cannot 
be too frequent ; for it is useless to place a large amount of dung 
in the soil to be converted into the substance of the turnip, unless 
the free action of the air is provided for at the same time, by 
which alone the decomposition of the dung can be effected. 

J. B. Lawes. 

Rothamstedy November, 1847. 



NOTB. — In placing raj name to this article, I mast observe that whaiteTer 
merit may be assigned to it is mainly dne to the skill and talents of Dr. 
OUbert, upon whom the responsibility attending the investigation has devolved. 
Those who have endeavoured to conduct with accuracy only a few experiments 
in agriculture wiU be capable of forming some estimate of the labour whieh so 
extensive a series requires. — J. B. L. 



PIimTKD BT 
SPOTTIBWOODB A5D CO^ NXW-STBOT SQVAJtS 

LOVPOJf 



EXPERIMENTAL INVESTIGATION 



INTO THB 

I 



I 



AMOUNT OF WATER GIVEN OFF 

BY PLANTS 



DURING THEIR GROWTH ; 



■iraCULLT IN BSLATIO!! TO 

THE FIXATION AND SOURCE OF THEIR VARIOUS CONSTITUENTS. 



By J. B. LAWES, 

or BOTHJLIfSTXD. 



LONDON: 
PRINTED BY W. CLOWES AND SONS, STAMFORD STREET 

AND CHARING CROSS. 

1850. 



RIPRINTED BY SPOTTISWOODB k CO., NEW-STREET SQUARE 

1694. 



FEOM THB 

JOUBNAL OP THB HORTICULTURAL SOCIETY OP L'^NDON. 

VOL. v., PART L (1860). 



AMOUNT OP 

WATER GIVEN OFF BY PLANTS 

DURING THEIR GROWTH. 



Op the several natural orders of plants which yield food to man, 
or to the animals destined for his consumption, or other use, per- 
haps the most important, both as to the extent of their distribu- 
tion and the amount of the products they supply, are the Oro- 
minacecB and the Leguminosoe, There are otiiers, however, to 
which we are indebted for the roots and tubers, the extended 
cnltivation of which, in alternation with grain, so prominently 
characterises at least the national agriculture of the present day. 
The corn-plants of most extended utility in the Leguminous 
family are the Bean and the Pea ; but we owe to it also some 
of the most important of our fodder-plants, such as Clover^ Tre* 
foil, Vetches^ and others. The Graminaceous family, on the 
other hand, supplies us with Wheatj Barley, Rye^ OatSy Rice, 
Maize, the Sugar Cane, and others, besides the natural grasses 
of our meadows and pastures. 

Between these two great natural orders of plants there are, 
however, many striking and obvious points of contrast as to 
habits, structure, and products, whilst the vastly different posi* 
tions allotted by experience to the individuals which they respec- 
tively comprise in a system of alternate cropping, are such as 
clearly to indicate that the resources of their growth are also 
widely different ; and it has been maintained that an explanation 
of them is mainly to be found in the varying mineral composition 
of the crops. The scattered observations, however, of many ex- 
perimenters, and some of not very recent date, would seem to 
&70ur an opposite view of the question, and the vastly accumu- 
kting published results of the last few years lend an ample con- 
firmation in the same direction. 

For our own part, an extensive and systematic series of experi- 
ments, conducted both in the field and in the laboratory, leaves 
not a doubt in our mind that, in the ordinary practice of agricul- 
ture in Great Britain, the exhauetion which is suffered is promi- 
nently connected with a deficiency of *' organic " or primarily 

B 2 



4 InvestigaMon into the Amount of Water 

aimospheric,, rather than the " mineral " or, more properly, 
soiUcouBtitxxents ; and especially that the supply of nitrogen, 
relatively to oilier constituents, is defective. We have already, 
in the * Journal of the Royal Agricultural Society/ indicated 
some striking facts bearing upon this point, in the discussion of 
the results of some of our experiments upon the growth and 
composition of Wheat and of Turnips. Beans, Peas, and Clover, 
as the types of the agricultural plants of the Leguminous family, 
have also been the subjects of experiment for several yeafrs past, 
and we hope before long to complete the results for publication. 
Besides the experiments of a more pnrely agricultural scale 
and character, however, it was thought that the explanation of 
the alternation of crops would materially be aided by any addi- 
tional information as to the characteristic qualitative and quantita- 
tive functional actions of some of the plants which ordinarily find 
a place in rotation. With this view, it was sought to ascertain, 
as in some degree a measure of the activity of the processes of the 
plants, the amount of water passed through those belonging to 
different natural orders, and holding different positions in rota- 
tion, both as compared one with another, and in reference to the 
quantitative fixation in the plants of several of their more im- 
portant constituents, having regard also, as far as was practicable, 
to the source of these constituents — that is to say, as to whether 
they were derived from the soil or from the atmosphere. 

The experiments, as thus far proceeded with, however, can be 
CQnsidered as little more than initiative, especially so far as the 
demonstration of those important agricultural problems, for the 
elucidation of which they have mainly been designed, is con- 
cerned: were it otherwise, indeed, the pages of this Journal 
would not be deemed the fittest medium for the publication of 
results of more purely agricultural interest. The facts already 
obtained, however, are not without interest to the botanist and 
the vegetable physiologist ; and it is as a contribution to the 
scanty information already at command, on the subject of the 
amount of water given off during the growth of plants, that these 
results are arranged and presented to the reader. It will never- 
theless be seen that they provide some important and interesting 
indications in reference to the more special object of our investi- 
gation, and at the same time afford some useful suggestions for 
its future conduct. 

, In deciding upon the method of procedure, the choice seemed 
to be between such experiments as would yield somewhat rapid, 
and in some points, perhaps, more direct information, though at 
the cost of the health and perhaps matured growth of the plant, 
on the one hand, and a closer imitation of the usual circumstonces 
of growth on the other — ^by which, however, inferences rather 



given off by Plants during their Growth. 5 

than demonstration might be elicited. The latter course was 
chosen, more especially as there are well-condacted experiments 
of the former Id^d on record, which it wss thought m^ht serve 
to check or confirm some conclusions which oar own results, 
taken alone, might be held not fully to justify. 

It was considered important to provide such conditions for the 
plants as should enable them to live and mature their seed, if 
such were the product for which they were usually cultivated — : 
an end not very easily accomplished in the case of plants growing 
through a period of several months, and requiring an accurate 
registry of the water passing through them. This was not, in* 
deed, in every case satisfactorily attained, as will be explained 
further on. But if, from this cause, any otherwise general indi- 
cations should seem to be opposed by figures, at first sight dis- 
crepant, a little further consideration may perhaps show that, if 
these are coincident with irregularities of growth and maturation, 
they may be taken rather as confirmations than as contradictions 
of any conclusions to which the results of the more naturally 
developed plants might lead us. We shall, however, submit to 
the reader a sufficient description both of the methods of experi- 
menting, and of the results, as they were actually obtained, 
whether numerically or by observation merely — leaving him, 
therefore, in a position to judge of the value of any suggestions 
we may offer, whilst the experience thus far attained will, it is 
expected, enable us to avoid in future some of the irregularities 
complained of, and the results then supplied will serve amply to 
confirm or correct any inferences at present hazarded. 

The plants selected for experiment were Wheat and Barley^ 
of the natural order Graminaceso; with Beans and Peas asCom- 
plants, and Glover as a Fodder-plant, from the Leguminosas — 
these several plants, moreover, occupying somewhat important 
and characteristic positions in a course of rotation. A Root' 
crof would also have been taken, but for the great and manifest 
difficulties of arranging the experiment. These we hope to 
overcome, however, in the coming season. 

The main desiderata in the arrangement of the experiments 
were — 

To provide the plants with soils of some known history and 

composition or resources, and in quantities sufficient to 

allow of a natural development of the roots. 
To prevent any serious amount of evaporation from the soil 

other than through the plants themselves. 
To have the means of supplying weighed quantities of water 

to the soils as it was needed. 
To determine by the balance the amount of water given ofi 

by the plant within any desired period of observation. 



6 Investigation into the Amount of Water 

To determine the total amount of water passed through the 
plant during the entire period of its growth ; and in rela- 
tion to this, the amounts of dry produce, and several of 
its constituents, fixed in the plant. 
To determine the source of these fixed constituents, iw^hether 
soil, manure, or atmosphere. 
We are prepared for the objections which may be raised 
against the means adopted for attaining the end and indications 
desired, and against the competency of the results, when obtained, 
to afford demonstration on some important points of the inquiry. 
Yet it is not unadvisedly that some of them, at least, have been 
risked, and especially in reference to the question of the exact 
composition and resources of the soils employed, do we not 
scruple to declare, though in opposition to the known opinions of 
several esteemed chemical friends, that we are more disposed, for 
the present at least, to rely upon the comparative indications 
which a natural and unanalysed but exhausted soil may yield 
alone, and in admixture with manures of known composition, 
than upon one of an artificial kind, such as pure sand, for ex- 
ample — or upon the results of analysis at the commencement of 
the experiments. Indeed, in proof of the dangers and uncer- 
tainty to which we are exposed in judging of the exact capabili- 
ties of a soil by its analysis, and especially of an exhausted one, 
wherein all the more important constituents are so small in quan- 
tity, we need only call attention to the very elaborate examination 
of this subject in the hands of Professor Magnus, as detailed in 
his account, ' Uber Versuche betreffend die ErschSpfung des 
Bodens.' 

The knowledge we obtain by synthesis in the method adopted 
and described further on, with the comparisons which will in 
time be provided is, we believe, our safer guide. Specimens of 
the soil, as originally taken for the experiments, are, however, 
preserved for analysis at some future time, when the whole sub- 
ject of the composition and properties of soils can be entered 
into — and when, also, by the continuous growth of the different 
plants as proposed, the balance of the constituents in the cases 
of the several experiments will be so far affected as to yield 
sufficiently wide variations, and therefore trustworthy points of 
comparison. 

As already stated, the plants selected for experiment were — 
Wheat, Barley, Beans, Peas, and Clover. Seeds of the first 
four of these were sown in a box of mould, where they were 
allowed to reach the height of about 3 inches before being 
transferred to the experimental pots ; but the Clover plant was 
brought direct from the field. One or more of each description 
of plant was grown in each of three different conditions of soil, 



given off by Plants during their Growth. 7 

and each set of the five plants with the same description of soil 
coDStitnted a Series. An inspection of the following plan will 
aid a conception of the arrangement of the experiments as to 
condition of soil and description of plant : — 

Wheat, 

Barleyi 

B(*an8f 

Peas, 

Clover, 

No plant. 

Wheat, 
Barley, 
Beans, 
Peas, 

^Clover. 

f Wheat, 

{Soil — as in Series 1, with the mineral Barley, 
manure of Series 2, and the Muriate of < Beans, 



Soil — from a plot of land from which ten 
Series 1 J successive grain-crops had been taken 

without manure (the larger stones being ^ 

silted out and the weeds picked) 

Soil — as in Series 1, with mineral manure, 
s««^o. o J containing Sulphate of Potash, Sulphate 

°^^^^^ < of Magnesia, Chloride of Sodium, and 

Superphosphate of Lime 



Ammonia added 



Peas, 
, Clover. 



Glass jars, 14 inches in depth and 9 inches in diameter, and 
which were capable of holding about 42 lbs. of soil, were the 
vessels employed. Six of these were filled with the soil as de- 
scribed for Series 1 ; five with that of Series 2 ; and five with 
that of Series 3 : there being in all, therefore, sixteen separate 
experimental jars. Into these, excepting the sixth jar o{ Series 
1, the plants raised, as described above, were transferred ; those 
from three seeds each of the Wheat and of the Barley being taken, 
and one plant only of the Beans, Peas, and Clover. A glass 
plate having a hole in the centre about three-quarters of an inch 
in diameter for the plants to grow through, and another nearer 
the side, by which to supply water as it was needed, and which 
was at other times closed by a cork, was then firmly cemented 
open the top of each of the sixteen jars. The sixth jar of Series 
1, however, though provided with soil and closed with a lid a4 
the rest, was left without a plant, as indicated in the tabulated 
plan above, in order to determine tlie amount of evaporation from 
the centre orifice. Each jar was placed upon a varnished board, 
for the convenience of attachment to the arm of the balance, and, 
as thas fitted and mounted, weighed little short of half a hun- 
dredweight. The jars on their stands constituting a Series were 
placed upon a truck, by means of which they were sometimes 
drawn into a green-house for the night, and under the balance 
when it was desired to weigh them, and on to a grass-plot during 
the day for free exposure to sun and air ; a canvas awning being 
provided, however, to protect them in case of rain. These 
arrangementfl will be clearly understood on inspection of the 



8 



Investigation into the Amount of Water 



annexed drawing, in which is represented a Series of the jars 
with their plants, fixed upon their scale boards, and placed apon 
their truck. 





The balance employed for weighing the plants was constructed 
for the purposes of these experiments by Mr. Oertling of London, 
and is calculated to turn with the third of a grain when loaded 
with from half a hundredweight to a hundredweight in each pan. 
A drawing of them is also given with a jar and plant as in pro- 
cess of being weighed. The knife-edge of the balance was 
relieved in the usual way by a support to the beam when not in 



given off by Plants during their Orowth. 9 

actnal use ; this being removed or applied at pleasure by means 
of a lever, the arrangement for which is not, however, indicated 
in the drawing. The whole was, moreover, covered by a frame 
of glass, provided with a door by which to gain access to the 
weight-pan, and another for the attachment of the loose arm by 
which the jar and plant are suspended. A standard counterpoise, 
consisting of two leaden weights, was kept in the weight-pan, 
the deviations only above and below this amount being deter- 
mined by weights — a set of which, from ten thousand grains 
down to on&-tenth of a grain, was provided for this purpose. 
As will shortly be seen, however, the amounts of water given oflf 
by the plants were very large ; and after a time it was not deemed 
necessary in practice to determine the weight within one grain, 
or frequently even two. 

Between the time of planting and the full growth of the plants 
more than twenty weighings of most of them were taken ; and 
weighed quantities of water were supplied whenever it seemed 
to be required. 

The collected results of the water supplied, or given off by the 
plants, are exhibited in the following tables : — 

In the Table (No. I.), page 10, as well as in those which follow 
it, the results are arranged in two sections ; the upper one bring- 
ing more prominently to view the comparisons between the dif- 
ferent plants with one and the same condition of soil, and the 
lower one those of the same description of plant with the vary- 
ing conditions of soil. 

The summary of the total water given off during the growth 
of the plants, as shown in the third column of this Table, is, of 
course, chiefly of interest in connection with the coincident accu- 
mnlation of vegetable substance, and it will therefore be repeated, 
and further considered, when we come to treat of that part of the 
subject. Attention may here be called, however, to the evidence 
afforded by a glance at the figures of this column — whether in 
the upper or the lower section — at the much greater regularity 
in Series 1 without manure, and in Series 2 witihi mineral manure 
only, than in Series 3 with both mineral and ammoniacal manures. 
Indeed, from the beginning, the plants of Series 3 were unhealthy, 
and, as indicated in the tables, only the wheat and the barley 
snrvived to the end of the experiment, and these even gave a 
produce far inferior to the same description of plants under the 
other conditions, though the ammonia provided by the manure 
amounted in this case to only about O'l per cent, upon the weight 
of the soil. 

It is seen that, in the cases of the healthy plants, there has 
been an average of about 100,000 grains of water given off by 
them daring their growth, an amount far greater than was anti- 
cipated 



10 



Investigation into the Amount of Water 



Table I. — Showixo the Total Amounts of Water supplied, derived from 
the Soil, and given off, during the entire period of the growth of the 
Plants. Quantities given in grains. 



Entire Period of 172 days, from March 19 to Sept. 7. 








Total Water 
Bui>plled. 


Total Water 
obtained 
from Soil. 


Total Water 
given off. 


Unmanured ... I 


Wheat 

Barley 

Clover (cut June 28th) 

Wneat ... • 

• Barley 

JPwcUlD •■« ••• ••■ 
X CAa ••• ••• ••• 

Clover (cui June 28ih) 

Wheat 

cariey ... ... ... 

Beans (died) 

Peas (died) 

Clover (cut July 4th) 


79,800 
88,800 
87,800 
81,800 
28,600 


33.727 
31,225 
24,431 

27,282 
26,593 


113.527 
120,026 
112,231 
109,082 
65,093 


With Mineral i 
Manure 


85,800 
97.800 
95,800 
86.000 
36,500 


12,206 
30.554 
22,069 
10,405 
17,223 


98,006 

♦128,334 

117,869 

96.405 

53,723 


With Mineral f 
and Ammonia- * 
cal Manure ... 


57,700 
74,300 

« • • • • 

• * • • « • 

24.300 


• • • • «  

10,824 

• • • • « • 

• • * • • • 

• • • • • • 


65,996 

85,124 

• • • • « • 

• • • • • » 

13,671 











Wheat 


Unmannred 

Mineral Manure 
Min. and Am. Man.... 

Unmanured 

Mineral Manure 
Min. and Am. Man.... 

Unmanured 

Mineral Manure 
Min. and Am. Man.... 

Unmanured 

Mineral Manure 
Min. and Am. Man.... 

Unmanured 

Mineral Manure 
Min. and Am. Man.... 


79,800 
85,800 
57,700 


33,727 
12,206 

• • • • • • 


113,627 
98.006 
65,996 


• 
Barley 

1 


88,800 
97,800 
74,300 


31,225 
30,554 
10,824 


120.026 

•128,364 

86,124 


Beans 


87,800 
95,800 
(died) 


24,431 
22,069 

... .•• 


112,231 

117,869 
••• ••■ 


Peas 


81,800 
86,000 
(died) 


27,282 
10,405 

• • « • • • 


109.082 
96.406 

... . • * 


9 

Clover 


28.500 
36.500 
24,300 


26,593 
17,223 

.•• . . « 


65.093 
53,723 
13,671 











* The glass lid was broken bj the pressnre of the plants, nnd the ioil therefore par^j ezpoeed. 



given off by Plants during their Growth, 1 1 

cipafed when the arrangements for the experiments were made ; 
and it will readily be understood that, with snch quantities as 
these, it was seldom necessary to conduct the weighings with the 
nicety for which we were prepared. 

The first and second columns of the Table show the sources 
of the water given off, from which it is seen that an amount 
varying from 10,000 to 30,000 grains has been derived from the 
soil, the remainder having been supplied as the experiment pro- 
ceeded. It should be remarked, however, that before the com- 
mencement of the experiment, 30 fluid ounces, or between 14,000 
and 15,000 grains of water, were added to each of the jars of soil, 
which, by exposure to the air for some time with shelter from 
the rain, and by the process of sifting, had become somewhat dry. 
The figures in the table therefore overstate, by nearly the quantity 
jast mentioned, the amount obtained from the normal soil. Never- 
theless it is believed that the wheat and the barley plants suffered 
to some extent during the latter period of the experiment for want 
of a freer supply of water, and that to this cause may in part be 
attributed a defective development of their seeds as compared 
riih those of the beans and peas. 

We have not prepared any detailed account of the periodical 
supply of water, which was regulated, both as to time and quan- 
tity, in part by the amount given off by the plants, and partly 
alio by their apparent or supposed requirements. It may be 
stated, however, that none was added during the first few weeks of 
the experiments, and that the doses given varied from 250 grains 
to as much as 1, 2, 3, 4, 6, or even 12 thousand grains as the 
growth of the plants progressed. 

A somewhat more detailed view of the amounts of water given 
off by the plants may be of interest, and we have accordingly 
supplied, in Tables II. and III. (pp. 12,13), statements both of 
the total and the average daily loss during periods, in the main, 
as nearly approaching to one month each, as the details of our 
registry would permit. 

The relationship of evaporation to rapidity of growth is, it is 
tnie, as yet a problem, but it may nevertheless be assumed as a 
general fact — and especially between plant and plant of the same 
description — ^thatthe comparative rate of the evaporation of water, 
or its amount within any given period, to some extent indicates 
the comparative activity of the processes of the plants; yet, since, 
with the advance of the season, and increased intensity of heat 
and light, the surface for evaporation was also constantly in- 
creasing, it is difficult to determine whether the increasing loss up 
to a certain period, as indicated in the tables, is, to any extent, 
materially due to the external influence referred to, irrespectively 
of a corresponding enlarged surface and rapidity of fixation of 

constituents. 



12 



Investigation into the Amount of Water 



Tablb II. — Showing the Number of Grains of Water given off by the Pliittb 

during stated divisional Periods of their Growth. 







9 Days. 


81 Daya 


27 Days. 


S4DayB. 


30 Daya 


14 Days. 


S7I>afi. 


Description of Plant and Manure. 


From 
Mar. 19 


Prom 
Mar. 28 


Prom 
April 28 


From 
May 25 


From 
Jmie 28 


From 
July 28 


Fnna 
Aug. 11 




to 


to 


to 


to 


to 


to 


to 




Mar. 28. 


Apr. 88. 


May 25. 


June 28. 


July 28. 


Aug. 11. 


Sepu 7. 


.Wheat 


129 


1268 


4,385 


40,030 


46,060 


15.420 


6,235 


Sbrtbr I — — ITn- 


Barley 


129 


1867 


12,029 


37,480 


46,060 


17.046 


6,4U 


ms) nni*nH 


Beans 


88 


1854 


4,846 


30,110 


58,950 


12,626 


3,657 


liJcLUUXOU ... 


Feas 


101 


1332 


2,873 


36,715 


62,780 


6,281 


• •  


V Clover 


400 


1645 

 


2,948 


50,100 


• • • 


• • * 


>• • 


/Wheat 

SERIES II.-Mi- ^^^J 
neral Manure ]p®*° 

> Clover 


106 


888 


3,935 


33,800 


41,200 


9,364 


8,713 


157 


2030 


11,249 


38,280 


51,830 


14,648 


10,260 


69 


1528 


4,790 


36,440 


59.680 


11,626 


4,706 


111 


1558 


4,249 


37,060 


61,520 


1,907 


• I • 


353 


1838 


5,008 


46,624 


• • ft 


« •  


• • • 










April 28 








" 








Ml 

June 28. 








.Wheat 


139 


866 


• •  


10,300 


27,710 


15,261 


2,a^o 


Series III.— Mi- 


Barley 


138 


853 


• • • 


27,270 


37,060 


]4,6U6 


6,207 


neral and Ammo- • 


Beans 


80 


1439 


1,851 


(died) 


• • • 


• • • 


  • 


niacal Manore ... Peas 

V Clover 


(died) 


•  • 


• • • 


• • • 


• • • 


• • • 


• • • 


• •  


• • • 


 • • 


« •  


• •  


• • • 


• • • 


No plant 


• • • • • • 


109 


633 


362 


1,374 


1,066 


300 


• •• 





9 Days. 


31 Days. 


27 Days. 


34 Days. 


30 Days. 


14 Days. 


27DSJS. 


Wheat 


Unmannred ... 
Mineral Manure 
Min.andAm.Man. 

r Unmannred ... 
Mineral Manure 
i Min.and AuLMan. 

Unmannred ... 
Mineral Manare 
Min.and Am Man. 

'Unmannred ... 
Mineral Manure 

^Min.and Am.Man. 

Unmannred ... 
Mineral Manure 
Min.andAm.Man. 


129 
106 
139 


1268 
888 
866 


4,386 
3,935 

• * • 


40,030 
33,800 
10,300 


46,060 
41,200 
27,710 


16,420 

9,364 

16,261 


6,236 

8.713 
2,030 


Barley  


129 
157 
138 


1867 

2030 

863 


12,029 
11,249 

» • « 


37.480 
38,^280 
27,270 


46,060 
61,830 
37,050 


17,046 
14,548 
14,606 


6,414 

10,260 

6,207 


Beans - 


88 
69 
80 


1854 
1528 
1439 


4,846 
4,790 
1,851 


30,110 
36,440 
(died) 


58,960 
69,680 

« • • 


12,626 
11,626 


3,667 
4,706 

• • « 


Peas ^ 


101 

111 
(died) 


1332 
1568 

• • • 


2,873 
4,249 

« • • 


36,716 
37,060 

« • • 


62.780 
61,620 

• • • 


6,281 

Cut 
Anp. 11. 

1,907 

Cut 
Aug. 4. 

• • a 


• • • 

• • • 


Clover • 


400 
353 

• » • 


1645 
1838 

t * • 


2,948 

6,008 

• < . 


60,10^) 
46,524 

 * • 


• t • 

• • • 

• « • 


• • • 

• • • 

• • • 


« • • 

• • t 

• • • 



given off by Plants during their G^'owtJi. 



18 



Table III. — Showino the AvEBAeE Daily Loss of Water (in Grains) by the 
Plaints, within several stated divisional Periods of their Growth. 







9 Days. 


31 Days. 


87 Days. 


34 Days. 


30 Days. 


14 Days. 


87 Days. 


Deteripckxn of Plant and Manmre. 


From 
Mar. 19 


From 
Mar. 88 


From 
April 88 


From 
May 86 


From 
June 88 


From 
July 88 


From 
Aug. 11 




to 


to 


to 


to 


to 


to 


to 




Mar. Sa 


Apr. 88. 


May 25. 


June 88. 


July 28. 


Aug. 11. 


Sept. 7. 


/Wheat 


14-3 


40-9 


162-4 


1177-4 


1636-3 


1101-4 


230-9 


. SiRlBS I. — Un- 
manured 


Barley 
Beans 


14-3 
97 


60-2 
69-8 


445-5 
179-5 


1102-3 
885-6 


1602-0 
1966-0 


1217-6 
901-8 


237-5 
136-4 


Peas 


11-2 


429 


106-4 


1079-8 


2092-7 


377-2 


• • • 


V Clover 


44-4 


53-0 


109-2 


1473-5 


• • • 


... 


• • • 


/Wheat 


11-8 


28-6 


145-7 


9941 


1373-3 


668-8 


322-7 


Skbtib II. — Mi- J 
neial Manure...' 


Barley 
Beans 


17-4 
7-6 


65-5 
49-3 


416-6 
177-4 


1125-9 
1042-3 


1727-7 
1989-3 


1039-1 
830-4 


3800 
176-4 


Peas 


12-3 


50-3 


1570 


1090-0 


1717-3 


136-2 


•«. 


' Clover 


39-2 


69-3 


186-5 


1368-3 


• • • 


• • • 


... 








April 88 to 
May 12. 


May 12 to 














June 28. 










/Wheat 


15-4 


27-9 


3731 

April 28 to 
May 9. 


108-0 

May 9 to 
June 28. 


923-7 


10680 


76-2 


Sebibb in.— Mi- , 
neial and Ammo-*^ 


Barley 


15-3 


27-6 


136-4 


616-4 


12350 


10433 


192-8 








April 28 to 










macal Manure... 








May 9. 












Beans 


8-8 


46-4 


168-3 


«• • 


fl • • 


• • • 


• •• 




Peas 


• • • 


• • • 


• • • 


• • • 


• • « 


 • • 


•  • 


^Clover 


• • • 


• • • 


• • • 


• • • 


« • * 


• • * 


•  • 


Kg Plant ... 


• • « •• • 


121 


20-4 


13-4 


40-4 


36-5 


21-4 


• • • 





9 Days. 


31 Days. 


27 Days. 


34 Days. 


30 Days. 


14 Days. 


27 Days. 


'Unmanured 
Wheat ^°®™^ Manure 
Min. and Am. Man. 


14-3 
11-8 

16-4 


40-9 
28-6 

27-9 


162-4 
146-7 

f 14 Days. 
1 373-1 


1177-4 
994-1 

47 Days. > 
108 0) 


16363 
1373-3 

923-7 


1101-4 
668-8 

10680 


230-9 
322-7 

75-2 


Barley- 


Unmanured 
Mineral Manure 

Min. and Am.Mau. 

Unmanured 
Mineral Manure 

Min. and Am. Man. 


14-3 
17-4 

15-3 


60-2 
65-5 

27-5 


445-5 
416-6 

1 11 DavH. 
\ 136-4 


1102-3 
1126-9 
50 Days. ) 
615-4) 


1602-0 
1727-7 

12350 


1217 6 
10391 

1043-3 


237-5 
380-0 

192-8 


Beans * 


9-7 
7-6 

8-8 


598 
49-3 

46-4 


179-5 

177-4 

f 11 Days. ) 

t 168-3 ) 


886-6 
1042-3 

• • • 


19660 
1989-3 

• • • 


901-8 
830-4 

• . . 


135-4 
176-4 

 • • 


^UnmanTired 
h»A ' Mineral Manure 
, Min. and Am. Man. 


11-2 
12-3 

• • • 


42-9 
50-3 

a • • 


106-4 
1570 

 • « 


1079-8 
1090-0 

 • • 


2092-7 
1717-3 

• • « 


377-2 
136-2 

« • • 


• • • 

• • • 
 • • 


CloTer 


[Unmanured 
Mineral Manure 
Min. and Am. Man. 


44-4 
39-2 

• * • 


63-0 
69-3 

• • • 


109-2 
186-5 

• • • 


1473-6 
1368-3 

« • • 


a • • 

• « • 

• • • 


• • • 

• • « 

• • • 


• « • 

• •• 

• • • 



14 Investigation into iJie Amount of Water 

constituents. So far, of course, as the process is one of simph 
evaporationy will an increase of temperature determine a greater 
loss of water ; still the question arises whether — supposing there 
be no actual deficiency of the necessary and available constituents 
— this increased passage of water through the plants, carrying 
with it in its course many important materials of growth from 
the soil, and probably also influencing the changes in the leaves 
of these, as well as of those derived from the atmosphere, will 
not be accompanied with an equivalently increased growth and 
development of the substance of the plant. Upon this point some 
light may be thrown by an examination of the circumstances 
attending the development of ** Roots," the more active growth 
of which is generally coincident with a declining and not an 
increasing temperature, as in the case of the seeding crops now 
under trial. 

Until, however, the relationship of the quantity of water given 
off to the amount of dry substance or its constituents fixed, under 
varied and known circumstances, be experimentally determined, 
any detailed consideration of the indications of the thermometer 
in connection with results of so initiative a kind would be un- 
availing, though a more or less complete registry was kept of the 
temperature during the period of the growth of the plants, and 
this point will not be neglected in our future progress. 

As might have been anticipated, it is seen by the Tables, that 
though, as the season advanced in temperature and the mass and 
surface of the plants increased, the amount of water daily given 
off was also greater up to a given time, yet towards the end of 
the experiment it rapidly and considerably diminished. It is 
probable that, from the time of this apparent decline in the rale 
of passage of water through the plant, the processes of acquirement 
of material were less active, those of the ripening and elaboration 
of its contents having commenced, and that the time of most 
active circulation, as indicated by the daily rate of water evapo- 
rated, was also that of the greatest accumulation. Some experi- 
ments which we conducted a few seasons ago, with the view of 
determining whether there was, in the formation and ripening of 
the cereal grains, any diminution in the amount of nitrogen pre- 
viously stored in the plant, seemed, indeed, to show, that though 
there was no appreciable change in the amount of the nitrogenous 
compounds upon a given area of land after the time of flowering, 
yet the amount of Tion-nitrogenous vegetable substance accumu- 
lated after this time had been very great ; it is not, however, 
necessary to conclude that the rapid accumulation of carbon from 
the atmosphere at this period, though coincident perhaps with an 
apparently less sucbulent condition of the plant, was in reality 
attained with any less degree of activity of the fluids within it. 



given off by Plants during their Growth. 1 5 

or of watery exhalation from it, than during the earlier stages of 
ite growth. Upon this point some information will probably be 
afforded by oar results as we proceed. 

The daily rate of evaporation in the cases of the two more 
healthy clover plants — ^those, namely, of Series 1 and 2 — is seen 
to be in the main higher, up to the time of their being cut, than 
in those of the other plants ; in explanation of which, it must be 
remembered that the clover experimented upon, being the produce 
of seed sown in the previous season, these plantd were, at the 
commencement, more advanced than those with which they here 
stand in comparison. 

The total evaporation from the jar without a plant is seen to 
be 3844 grains during the entire period of the experiment. This 
total loss from the hole in the glass lid is certainly considerable, 
but it amounts on an average to little more than 3 per cent, of the 
entire quantity given off from the jars containing the plants, and 
it seems unsafe on several grounds to attempt to correct the indi- 
cations of the latter by the deduction of the amount of loss from 
the no-plant jar. Thus, the loss from the centre-hole of the no- 
plant jar might be supposed to exceed that from the rest, since 
in these the orifice was nearly closed by the stems of the plants; 
bnt^ on the other hand, the much less active circulation of air 
through the unplanted jar would tend to an opposite result, as 
also would the fact, that in the absence of a fresh supply of water 
in this case, the surface of the soil would, after a time, become 
somewhat dry. That this was the case would appear from the 
figures in the Table, which show that though the rate of loss from 
the no-plant jar increased for a length of time as the season 
advanced, yet afterwards it to some extent diminished. It may 
be remarked, however, that there was frequently in this case, as 
well as in the others, a condensation of water on the under surface 
of the lid. Upon the whole, then, we are inclined to decide, 
that the indications of this experiment should serve rather to 
prevent any too nice application of the numerical results obtained 
in relation to the plants, than as providing any available means 
of correcting them. 

Let us now turn our attention to the amount and composition 
of the produce obtained from the experimental jars. The wheat 
plants in all three of the jars appearing sickly from the time of 
transplanting, were cut down twelve days afterwards, viz., on 
March 31st, in the hope that they would then grow up more 
vigorously. These cuttings, when dried at 212**, in neither case 
weighed one grain, but they were saved, and their quantities are 
taken into account with the rest of the produce. Stems were 
also cut from the wheat grown by the unmanured and the mineral 
mauured soil, as well a s from all of the barley jars, on May 26th ; 



16 Investigation into the Amount of Water 

the holes in the glass covers having become in these cases quite 
choked np. These cuttings were much more considerable in 
quantity than the former, and of course also considered as a part 
of the experimental product. 

The several clover plants were respectively cut when in full 
flower. The pea with mineral manure was cut on August 4th, 
and that in the unmanured soil on August 11th. All the other 
plants, viz., wheat, barley, and the beans, were harvested on 
September 7th. 

The com of the peas and beans was well developed and 
tolerably ripened : that of the wheat and the barley was by no 
means so much so, especially that of the wheat. This was sap- 
posed partly to arise from a want of water, the plants having an 
appearance of drying up rather than healthy ripening. It is seen, 
indeed, by reference to Table I., at page 10, that the amounts of 
water derived from the soil were greater in the cases of one of 
the wheat jars and two of the barley jars than in the others, 
though the exhaustion, in this respect, of the beans, one of the 
peas, and one of the clovers, was not much less. It had been 
remarked, however, from the commencement, that the apparent 
demand for supplied water was much greater in proportion to 
that given off in the cases of the graminaceous plants than in the 
several leguminous ones ; but it seems generally to have been 
found by experimenters, that the cereals were much more diffi- 
cult to bring to maturity under the somewhat artificial circum- 
stances usually provided in experiments of this kind, than any 
other plants. 

The irregularities of cuttings and want of uniformity in the 
final maturation of the produce will be guarded against as far as 
possible in our future experiments. To these indeed may pro- 
bably be chiefly attributed any want of definiteness or consistency 
in the results about to be considered ; and it was on account of 
them deemed unnecessary to take the fresh weights of the produce 
of the jars. 

The plants cut level with the surface of the perforated lids, 
shortly after being taken from the jars, were dried in a stove 
at about 140"*, and then carefully stored for future examina- 
tion. 

Recurring to the subject for the purpose of this paper, the 
corn plants were carefully dissected — the seeds from the straw, 
chaff, &c. Each of them was then exactly halved. The one 
portion of com, and one each of straw, chaff, &c. (the latter being 
mixed together), were fully dried at 212** — the weight taken and 
then burnt to ash, and the other specimens, the com separately 
from the straw, chaff, &c., being reserved for the determination 
of their nitrogen. The cuttings were also halved and treated in 



given off hy Plaiiis during their Growth. 



17 



like maimer, those taken at different periods from the same plant 
having been mixed. 

In Tables IV., V., and VI., are given the results of the dry- 
ings and burnings of the produced plants. 

Table IV.— Quantities (in grains, tenths, &c.) of Dbt Matter fixed in the 
several parts of the Plants, and in the Total Produce of the Jars, &c. 



Description of Flanti and Manure. 



In Com. 



» « • •  • * < 



{Unmanared ... 
Mineral Manure 
Mineral and Ammon. Manure 



148-5 

; 111-2 

65-4 



I • • • 1 



fUnmanured ... 

Barley < Mineral Manure 

t Mineral and Ammon. Manure 



Beans 
Peas 



fUnmanured 

\Mlneral Manure 

/ Unman ured 



« • • VI 



i Mineral Manure 



{Unmanured 
Mineral Manure 
Mineral and Ammon. Manure 



In 

straw 

and 

Chaff. 



302-8 
3219 
206-2 



188-7 
1790 
112-8 



282*6 
' 2990 



253-74 

2970 

170-6 



254-9 
238-8 



In 
Chit- 
ting*. 



7-6 
7-6 
t>-3 

231 
24-6 
29-8 




In Total 
Produce 



468-9 
440-7 
271-9 

465-54 

600-6 

313-2 

637-5 
637-8 



Proportion 
of Corn to 

100 of 
Straw, &c. 



47-84 
33-74 
31-67 



421-0 
457-4 



68-16 
56-66 
66-34 

110-86 
125'20 

104-07 
87-76 



204-7 
234-8 
92-6 



Table V. — Quantities Qji gprains, tenths, &c.) of Minebal Matter fixed in 
the several parts of the Plants, and in the Total Produce of the Jars, &c. 



Deacription of Plants and Manure. 


In Com. 


In Straw 
and Chaff. 


In 
Cutting*. 


In Total 
Produce. 


Unmanured ..• ..• « 

Wheat • Mineral Manure 

Mineral and Ammon. Manure 


4-22 
3-06 
216 


30-62 
40-44 
29-74 


1-66 

1-44 
0048 


36-49 
44-94 
31-948 


'Unmanured 

Barley Mineral Manure 

Mineral and Ammon. Manure 


6-2 
6-8 
4-72 


36-38 
39-22 
2406 


8-34 

46 

4-4 


46-92 
50-62 
3318 


^Mineral Manure 


9-02 
10-6 


40-0 
3616 


• • • 

• • • 


49-02 
46-76 


p fUnmanured 

\Mineral Manure 


6-76 

8-24 


36-4 

56-98 


• • • 


43-16 
64-22 


CloTer 


Mineral Manure 

Mineral and Ammon. Manure 


• • • 

• • • 

• • • 


• • • 

• • • 

• < • 


• • * 

• • a 
« • • 


29-24 
36-48 
13-10 



18 



Investigatiwi hvto the Amomvt of Waier 



Table VI. — PEBCEirrAGEs of Ash in Dbt Matter. 



Description of Plants and Mannre. 



In Gorn.l 



•  < • 



rUnmanured 

Wheat ■{ Mineral Manure 

[ Mineral and Ammon. Manure 



2-84 
275 

3-30 



In Straw 
andCbaff. 



1011 
12-66 
14-42 



In 
Cattings. 



21-71 
18-95 
160 



In Plant 

(dOTCT). 



Barley  


^ Un manured 

Mineral Manure 

Mineral and Ammon. Manure 


3-28 
3-80 
4-18 


14-34 
13-20 
14-1 

16-69 
1614 


14-46 
18-70 
141 


• • • 
 • • 

• • m 


„ „^ rUnmanured 

Jieans ^jj.^gj.^ I^^^^j^ 


3-19 
3-56 


1 
ft • • 

•   


« • • 
• • • 


■J, fUnmanured 

1 eas 'i^ Mineral Manure 


316 

3-85 


17-64 
230 


•  • 

• • • 


• • • 

• • • 


C'lover ' 


Unmanured 

Mineral Manure 

Mineral and Ammon. Manure 


• •  
 • • 

• •  


•  • 

•  • 

• • • 


• • • 

• • • 

• • • 


14-28 
15-11 
1415 



In Table IV. the dry matter in the several part^ of the speci- 
mens is given, the quantities being calculated upon the entire 
produce of the jars. Excluding the clover-plants, which do not 
compare fairly with the rest, and those also having the ammo- 
niacal manure, which were evidently injured by it, we see at 
least some general uniformity in the amount of dry matter pro- 
duced ; the beans, however, which were of all the plants the 
most healthy, yielding not only an amount almost identical with 
the unmanured and the mineral-manured soils, but higher than 
any of the rest. And if we refer to the last column of the 
Table, we see that in their cases especially, but also notably in 
those of the peas, the seed (which in both is so highly nitro- 
genous) shows a much higher proportion to the entire produce 
than in the cereals. 

These actiuil quantities of dry matters produced, though indi- 
cating, perhaps, to some extent the healthy development of the 
several plants under the conditions provided for them, will bo 
more conveniently studied in their relationship to the amount of 
water given off, when calculated to a uniform standard, as in the 
Table which will shortly follow. 

The figures of Table V., indicating the actual amounts of 
mineral matter fixed in the plants, are also of little independent 
interest. Those of Table VI. show the percentage of mineral 
matier in the gross dry substance in the several plants and parts 
of plants, and indicate it to be in every instance higher than is 
usual ; though less so in the Leguminous seeds than in the 



19 



r 

I yiven off by Plants during their Growth. 

I cereals, and more in the wheat than in the barley. The propor- 
r tion is seen, moreover, to vary in the same description of plant 
with the different conditions of soil, it being generally higher 
where mineral manure was employed than with no manure. 
This general excess of mineral matter may be taken as being 
connected, to a great extent, with the defective state of ripening 
of the plants, and between plant and plant of the same descrip- 
tion the amount of it may indicate their relative qualities in this 
respect. 

Table VII. — Table of Actual Experimental Rbsxtltb. 







Number 

of 
Gndns 

of 

Water 

given off. 


Number of Grains fixed in the 
Plant, of— 


BeacriptioD of Plant and Manure. 


Dry Matter. 


Mineral 




Inclnsiye 
of Ash. 


Organic 
only. 


Matter 
(Ash). 


UnmaoiiTed 


r Wheat 

Barley 

Beans 

Peas 

Clover 


113,627 
120.026 
112,231 
109,082 
66,093 


468-9 

466-64 

637-60 

421-00 

204-70 


422-41 
419-62 
488-48 
377-84 
176-46 


36-49 
46-92 
4902 
4316 
2924 


/Wheat 

Barley 

Mineral Manure ... - Beans 

Peas 

Clover 


98,006 

128,364 

117,869 

96,406 

53,723 


440-7 

500-60 

637-80 

467-40 

234-80 


395-76 
449-98 
49104 
393-18 
199-32 


44 94 
60-62 
4676 
64-22 
35-48 


Mineral and ATomo- 
niacal Manure ... 


W^neat ... 

Barley 

Clover 


56,996 
86,124 
13,671 


271-90 

313-20 

92-60 


239-952 
28002 
79-60 


31-948 

3318 

1310 



Wheat ... 



Barley.., 



^Unmanured 

•{ Mineral Manure 

(Min. and Ammon. Manure.. 

[Unmanured 

-I Mineral Manure 

(Min. and Ammon. Maaure.. 



Benns ... 



Peas 



iUnm?»nured ... 

i Mineral Manure . 

lUnmanured ... . 

*" 1 Mineral Manui-e . 



/Unmanured ... . 
CloTor ... J Mineral Manure . 

iMin. and Ammon. Manure., 



• • at 



113,527 
98,006 
55,996 



120,025 

128.354 

85,124 



112,231 
117,869 



109,082 
96,405 



. 55,093 
53,723 
13,671 



468-9 
440-7 
271-90 



465-54 
500-60 
31320 



587-60 
637-80 



421-00 
457-40 

204-70 

234-80 

92-60 



422-41 
396-76 
239-962 



419 62 
449-98 
280-02 



36-49 
44-94 
31-948 



488-48 
49101 

377-84 
39318 



45-92 
5062 
33-18 

4902 
46-76 

43- 16 
64-22 



175-46 i 29 24 

199-32 j 35-48 

79-50 13-10 

c 2 



20 



Investigation into tlie Amount of Water 



In Table VII. (p. 19) the total amoants of water given off 
during the growth of the plants, and the total amounts of dry 
matter, both inclusive and exclusive of ash, and of the, ash itself, 
are given side by side. The relationship of the water given off 
to the matter fixed in the plant is, however, more clearly indi- 
cated in Tables Yin. and IX. 



Table Vin. — Snowixe the QuantitieB of Subbtakobb fixed to a Standard 

Amount of Water given oif. 







Number of Grains fixed in the 
Plant for 100.000 Grains of 
Water given off, of— 


Description of Plant and Manure. 


Dry Matter. 


Mineral 




Inclusiye 
of Ash. 


OrKanio 
only. 


Matter 
(Ash). 


Unmannred 


rWheat 

Barley 

Beans 

Peas 

Clover 


404-2 
387-8 
478-9 
.'J8?l-9 
371-5 


372 
349-6 
435-2 
346-4 
318-6 


32-14 
38-26 
43-67 
39-57 
5307 


/Wheat 

Barley 

Mineral Manure • Beans 

Peas 

Clover 


449-7 
390-0 
456-3 
474-4 
4370 


403-8 
850-6 
416-6 
407-8 
3710 


46-85 
39-44 
39-67 
66-61 
66 04 


Mineral and Ammoniacal 
Manure 


fWheat 

Barley 

L/ lover ••« ••• ••• 


485-6 
.S67-9 
677-3 


428-6 
323-9 
581-5 


5705 
38-98 
95-82 



> • • • • • 



Wheat... 



Unmanured 

Mineral Manure ... 

Mineral and Ammoniacal Manure ... 



• • •  « • 



• • • • •  



• » • • • • 



■•• ••« «•• 



^Unmannred... 
Barley .,, < Mineral Manure... 

(Mineral and Ammoniacal Manure ... 



Beans i Unmanured... 
^'^^^ — t Mineral Manure 



T>A« . i Unmanured . . . 

reas ... 1 Mineral Manure 



Clover .., 



»•< ••• •■■ 



» * • • • • 



'Unmanured... 
Mineral Manure 
Mineral and Ammoniacal Manure .., 



•   • • • 



404-2 
449-7 
485-6 



387-8 
3900 
367-9 

478-9 
456-3 



385-9 
474-4 



371-6 
4370 
677-3 



3720 
403-8 
428-5 



349-6 
3506 
328-9 

436-2 
416-6 



346-4 
407-8 



3186 
3710 
581-5 



3214 
45-85 
6705 



38-26 
39-44 
38-98 



43-67 
39-67 



39-57 
6661 



53-07 
6604 
95-82 



given off by Plants during their Growth. 



I 21 



Table IX. — SHOwnve the Qaautitiea of Water giyen off to a Standard 

Amount of Si7B6TAKC£8 fixed. 



Description of Plant and Manure 



Unmanaied 



Mineral Manore 



Wheat 
Barlej 
Beans 
Peas ... 
Clover 

Wheat 
Barley 
Beana 
Peas ... 

Clover 



Mineral and Ammoniacal f ^^^ 
^"^"^ [clover 



• • • • • • 



  • • • • 



• • • A •  



 • « • • • 



• • • • • • 



• • » • • » 



Number of GrainB of Water given 
off for One Grain fixed in the 
Plant, of— 



Mineral 
Matter 
(Ash). 



• t • •  • 



Dry Matter. 


Incluslye 


Organic 


of Aah. 


only. 


247-4 


268-8 


267-8 


2860 


208-8 


229-7 


2591 


288-7 


2691 


3140 


222-4 


247-6 


256-4 


286-2 


219-2 


240-0 


210-8 


245-2 


228-8 


269-5 


205-9 


233-4 


271-8 


3040 


147-6 


1720 



3111-2 
2613-8 
2289-6 
2627-3 
1884-2 

2180-8 
2635-6 
2620-7 
1501-2 
1514-2 

1752-7 
2565-5 
1043-6 



Wheat ... 



• • « • •.• 



Unmannred ... 

Mineral Manure ... 

Mineral and Ammoniacal Manure .., 



■•• ••• ••• ••< 



Barley ... 



• • • • I 



I • ••! 



Beans ... 



'Unmannred 

Mineral Manure 

Mineral and Ammoniacal Manure ... 



t Unmanured 

1 Mineral Manure .. 



Peas 



f Unmanured 

" i Mineral Manure .. 



(Unmanured 
Mineral Manure .. 
Mineral and Ammoniacal Manure ... 



••• ••* ••) 



247-4 
222-4 
205-9 



257-8 
256-4 
271-8 



208-8 
219-2 



269-1 
210-8 



2691 
228-8 
147-6 



268-8 
247-6 
233-4 



286-0 
285-2 
304-0 



229-7 
240-0 



288-7 
2462 



314-0 
269-5 
1720 



3111-2 
2180-8 
1762-7 



2613-8 
2535-6 
2565-5 



2289-5 
2520-7 



2627 3 
1601-2 



1884-2 
1514-2 
1043-6 






In Table VIII. there are shown the amoaiits of gross dry sub- 
stance, of dry organic matter, and of mineral matter fixed, for 
every 100,000 grains of water carried oflT from the soil by the 
plants, and in Table IX. the amount of water given off for the 
fixation of one grain of each of these is indicated. 

The indications of these Tables are certainly not without the 
appearance of discrepancy : yet when we remember the circum- 

c3 



22 Investigation into the Amount of Water 

stances of irregalarity of growth already fully detailed, and also 
the greatly varying products, of whidi the substance of the 
plants is in several cases made up, the general uniformity of the 
figures is sufficiently striking, and calculated to lead to the ex- 
pectation of much more definite results in future, and more care- 
fully conducted experiments. 

Referring first to Table VIII., and taking the upper section of 
it, we see that the amounts of dry matter produced to 100,000 
grains of water given off by the plant, range in the case of the 
wheat, the barley, the pea, and the clover, in the unmanured 
soil, between 371 and 404 grains; or, excluding the clover, 
between the latter number and 386 grains, an approximation 
sufficiently indicating some definite relationship between the 
passage of water through the plant and the fixation in it of some 
of its constituents. The bean in this series seems to be an ex- 
ception, the amount of dry substance produced in this case being 
about 479 grains, or nearly one-fourth more than the average of 
the other unmanured plants. When we remember, however, the 
much larger amount of nitrogenous compounds which this pro- 
duct would contain than any of the other specimens, we see 
that, with this variation in the amount of vegetable growth 
to a given quantity of water evaporated, there is, at least, coin- 
cident variation in the composition of the product itself; and 
the particular facts would lead to the suspicion, that the water 
evaporated had a more definite quantitative relationship to the 
fixation of the ?ion-nitrogenous than to that of the nitrogenous 
constituents of the plants. 

Looking at the results of the second Series (with mineral ma- 
nure), we see a generally higher amount of dry substance pro- 
duced for a given circulation of water than in Series 1 ; and 
also, the barley excepted, a much greater uniformity than in the 
former Series. The cause of this discrepancy in the barley may 
perhaps be explained by the fact already mentioned, that the lid 
of the jar in which it grew had been broken during a consider- 
able period of the experiment ; and though the pieces were 
cemented together, yet it is more than probable that water 
was lost from the soil by evaporation through the crack, in 
which case the amount of product would necessarily appear 
low. 

In the case of this Series, too, it is seen that the product of 
beans is exceeded by the peas, and nearly reached even by the 
wheat. On the view referred to above, therefore, it would be 
necessary to suppose that, provided the results are to be relied 
upon, the composition of the several products as regards nitrogen 
would be more nearly equal in the case of this Series than in the 
former one, and also that the percentage of it was higher in the 



given off by Plants during their Orowth. 23 

specimens of the second Series than in those of the first — a 
result which would have to be attributed to the more or less 
direct influence of the manure. 

The plants of Series 3, having an ammoniacal manure, were 
so manifestly unhealthy that the results afforded in relation to 
them mast not be allowed much weight, and indeed they appear 
to be little worthy of confidence. 

In the lower section of Table VIII. the comparison is made 
between the individuals of the same description of plant under 
different conditions of soil. A considerable difference is here 
shown to be coincident with the variations of manuring condition, 
and, setting aside the clover, more especially in the cases of the 
wheat and the peas. The composition of these when determined 
may, to a great extent, elucidate the fact ; indeed, the varying 
proportion of seed to straw in the several cases indicates a pro- 
bable difference in this respect ; and analogy would also lead us 
to believe that, with the varying observed degree of ripeness and 
the experimentally ascertained varying amounts of ash, the per- 
centage of nitrogen in the several specimens of the same kind of 
plant would also vary very greatly. In support of this opinion 
we may state that analyses already made of some of the products 
show that some of the cereals contained nearly twice the ordinary 
amount of nitrogen. The coincidences in this section are most 
striking in reference to the beans, and these, as has been already 
stated, were the most healthy and matured plants obtained from 
the experimental jars. The three barley plants, it is true, show 
a considerable uniformity, but, as has already been explained, 
the figures given for the mineral manure plant are probably 
somewhat in error. 

Notwithstanding these discrepancies, as yet not fully and satis- 
factorily explained, we cannot but recognise in the results thus 
far obtoined a very encouraging significance ; and, indeed, it 
seems to us more than probable that future experiments may fix 
a definite relationship between the amount of water given off and 
that of the nor^nitrogenous proximates fixed in the plant, and 
this even probably to a great extent irrespectively of their exact 
composition, provided their source were mainly in each case the 
atmosphere^ as in the instances of the seeding plants now under 
consideration, and accumulating, as they are known to do, their 
chief supplies during the period of the most powerful influence 
of heat and light upon the plants. 

In Table IX. the amounts of water passing through the plant 
for each grain of substance fixed are given — the indications 
being the inverse of those we have just been considering ; and 
the differences are of course dependent on the same circumstances 
as those already alluded to. 



24} Investigation into the Amount of WcUer 

It is a striking fact, that (excepting a single clover plant, which 
was always anhealthy) there is in every case more than 200 grains 
of water passed through the plant for one grain of material accn- 
mulated. 

Referring to the column of water evaporated to mineral matter 
fixed, we see the amount of the former to be, on an average, 
2000 times that of the latter. Whatever other explanation, there- 
fore, we may receive as to the conditions of assumption by the 
plant of some mineral substances occurring in it, in insoluble 
combinations, we have here evidence sufficient to show that few 
of the substances required by plants, and which are generally 
assumed to be insoluble, are incapable of being taken up by 
them in an adequate quantity in rain water. 

It was our hope to have given in this paper the results of the 
determinations of nitrogen, in the various specimens grown in 
the pots, with the view of showing what relation subsisted 
between the amount of nitrogenotis proximates fixed in the plant, 
and that of the water passed through it. Unfortunately, how- 
ever, the laboratory work in connection with this branch of the 
inquiry is as yet not so far advanced as to justify the discussion 
of the numerical results on this occasion, nor will our allotted 
time allow us to do so. We may, however, state that, as fSso* as 
our results have gone, it would appear that, whilst for a given 
quantity of water evaporated the amount of Ttori-nitrogenous sub- 
stances fixed in the plant is within somewhat narrow limits 
identical, in the specimens now under experiment of the two 
natural orders of plants, that of the nitrogenous proximates fixed 
is, on the other hand, about twice as great in the Leguminosse as 
in the Graminaceaa. This is indeed a significant fact, as bearing 
upon the distinctive functional characters of the various plants 
which enter into rotation. It is, moreover, perfectly consistent 
with th** results of our experiments in the field with wheat and 
beans respectively, which show that, under the same circum- 
stances of growth, as to manure, &c., and in the same season, 
the acreage yield of nitrogen is twice or thrice as great in beans 
as in wheat. 

It cannot be supposed, however, that with the larger amount 
of nitrogen harvested in the Leguminous crop the soil would be 
proportionally exhausted of it, for common practice sufficiently 
teaches that, other things being equal, a larger produce of wheat 
would be obtained after a bean than after a wheat crop, not- 
withstanding its known dependence on the supply of nitrogen in 
the soil. 

It may be supposed, indeed, that here we have evidence of a 
superior power in the Leguminous as compared with the Grami- 
naceous plants, of obtaining their nitrogen from the atmosphere 



given off by Plants during their Gh'owth, 25 

rather than from the soil. However this may be, many experi- 
ments of our own have convinced ns that, especially in the 
growth of the Graminaceous grains, there is never an increased 
acreage yield of nitrogen in any degree approaching that supplied 
by manure ; and, independently of results of a more direct and 
practical kind, it has been observed by several experimenters, 
that during the growth of plants there is a constant evolution of 
nitrogen from their leaves. 

Thus De SausBure, in his ^Recherches Chimiques sur laV6g6- 
tation/ pp. 40-43, gives the results of experiments on this subject, 
and he comes to tiie conclusion that the amount of nitrogen given 
off bears a direct relation to that of oxygen assimilated by the 
plant &om the absorbed carbonic acid. His experiments, more- 
over, were made with the Veich^ which, as will be remembered, 
is a member of the Leguminous family of plants, in which, as 
compared with the Graminaceous family, we would suppose the 
evolution of nitrogen to be less considerable. 

Daubeny, again, in his ' Memoir on the Action of Light upon 
Plants, and of Plants upon the Atmosphere,' in the ' Philosophical 
Transactions for 1836,' Part L, arrives at a somewhat similar 
result; whilst more recently Draper, in his 'Chemistry of Plants,' 
pp. 184, 185, and context, ascertained in several experiments the 
amount of nitrogen given off during the growth of plants, and 
seeks to establish the following conclusions : that '' when the 
leaves of plants under the influence of light decompose carbonic 
acid, they assimilate all the carbon, and a certain proportion of 
oxygen disappears ; at the same time they emit a volume of 
nitrogen equal to that of the oxygen consumed,* This disap- 
pearance of oxygen and appearance of nitrogen are thus con- 
nected with each other : they are equivalent phenomena. The 
emission of nitrogen is thus shown not to be a mere accidental 
result, but to be profoundly connected with the whole physio- 
logical action At this stage of the inquiry a remarkable 

analogy appears between the function of digestion in animals and 
the same functions in plants. Liebig has shown how, from the 
transformation of the stomach itself, food becomes acted upon, 
and is turned into chyme ; an obscure species of fermentation, 
brought about by the action of nitrogenized bodies. So in like 
manner, in plants, the decay of a nitrogenized body is intimately 
connected with the assimilation of carbon ; for, as I have stated, 
the process here under discussion is a true digestive and not a 
respiratory process. And as there are facts which seem to show 
that the primary action of the light is not upon the carbonic acid, 
but upon the nitrogenized ferment, the decomposition of the gas 

* The italics are those of the author. 



26 Investigaticni into Vie Amount of Water 

ensuiDg as a secondary result, is it not probable tliaJL ChlorophyIi 
18 the body which in vegetables answers to the Chyle of animcdtf ? 
The oxygen which disappears during the decomposition of car- 
bonic acid, disappears to bring about the eremacausis of the nitro- 
genized body. And have not the gum, the starch, the lignin, 
and other carbonaceous constituents of plants, all originally 
existed in and passed through the green stage ? " 

Mulder, again, from purely chemical considerations, and, like 
the observers alluded to above, altogether independently of the 
important practical application of the phenomena to which we 
wish to direct attention, admits the constant evolution of nitrogen 
during the growth of plants, and that the source of this nitrogen 
must obviously be the compounds containing it already existing 
in the plants; but he maintains, with more or less apparent 
reason, that the relation of nitrogen given oflF to that of oxygen 
assimilated from the absorbed carbonic acid must depend mate- 
rially upon the composition of the compounds to be formed. 
Thus, referring to Draper's experiments, he says (see his * Che- 
mistry of Vegetable and Animal Physiology,' Part IV., p. 778), 
^' But this simplicity of relation is in my opinion accidental. 
The carbonic acid is employed for the production of various 
organic bodies, which cannot possibly be the same in all plants. 
Consequently, the quantity of oxygen given oflF cannot be a con- 
stant one. This variety of product also renders it impossible 
that a constant amount of nitrogenous substance should be re- 
quired for the decomposition of the carbonic acid." 

It may be taken, then, as a well-ascertained fact, that the 
evolution of nitrogen is a constant and coincident attendant on 
the growth and accumulation of a plant ; whilst it would seem 
that both the results of practice and the reasonings of the chemist 
would lead us to suppose that this loss is greater in some cases 
than in others. 

Let it once be admitted in agricultural science that there is a 
definite expenditure or consumption of the nitrogenous bodies 
derived through the roots connected with the fixation and elabo- 
ration of certain constituents of plants, and that this is greater 
or less according to the sources or the exact composition or state 
of elaboration of the products, and an importaiit step will be 
gained towards a clearer conception of the principles involved in 
the alternation, in a course of cropping, of plants of varying 
products and habits of growth. In one of our papers On Acpri- 
cultural Chemistry in the 'Journal of the Royal Agricultural 
Society' (Part I., 1847), we have ventured an opinion as to the 
probable amount of nitrogen required in the manure of wheat to 
yield a given amount of it in the increased produce. Since that 
time we have accumulated much additional evidence on this 



given off by Plants during their Gh^owth. 27 

point, which will enable bs to modify or confirm the estimate 
abeady hazarded, but which it is not the object or the province 
of this paper to discuss: the results yet to be obtained, however, 
in continuation of the inquiry constituting the subject of this 
report, will, it is anticipated, furnish further data bearing upon 
this important question. 

Before concluding these observations, it seems fitting to call 
attention to some incidental, yet important indications of these 
and other of our experiments. Granting, as the conjoint results 
of the field and of the experimental plants here under discussion 
would show, that, under equal circumstances of growth, and 
coincidently with the passage into the plant of the same amount 
of aqueous fluid fix)m the soil, the Leguminous plants will yield 
a pit)duce varying but little in gross amount from that of the 
GraminacesB, but containing a much higher percentage, and, 
consequently, total quantity of nitrogen, it would, on the view 
that the analysis of a crop should indicate the manure required 
for its growth, at once be decided that, of their organic con- 
stituents, the Leguminous plants should be liberally supplied 
with nitrogen^ and the Graminacea3 rather with carbon. But is 
this consistent with common usage or the dictates of experiment ? 
The low nitrogenized and highly carbonaceous Graminaceous crop 
requires for its luxuriant growth a large supply of nitrogen by 
manure ; but with this it seems practically independent of sup^ 
plied carbon, whilst the highly nitrogenized Leguminous plants 
are, other things being equal, by no means strikingly benefited 
by nitrogenous manures. We had, indeed, at one time supposed 
that clover was greatly dependent on an artificial provision of 
nitrogen, but this view does not appear to be favoured by further 
investigation ; whilst with it, as well as with those Leguminous 
plants valued in agriculture for their seeds, a mineral, and espe- 
cially an alkaline manure, seems to be more prominently indi- 
cated. 

Again, judging from the composition of the ash of the turnip, 
which shows both in the leaf and in the ** root " a proportion of 
alkalies to phosphoric acid of 4 or 5 to 1, we should be led to 
decide that the former, rather than the latter, were usually and 
specially the more appropriate manure for the turnip. Common 
practice has, however, definitely determined in favour of phos- 
phoric acid rather than on the alkalies. 

Indeed, the whole tendency of agricultural investigation seems 
to show tiie fallacy of alone relying upon the knowledge of the 
composition of a crop, as directing to the constituents probably 
more specially required to be provided for it by manures, and 
rather that the elucidation of agricultural principles must be 
looked for from a due consideration of vegetable physiology as 



28 Waier given off by Plants during their Orowth. 

well as chemistry — of the special functional peculiarities and 
resources of different plants, as well as their actual percentage 
composition. 

We are convinced, indeed, that however important and useful 
miscellaneous agricultural analyses may be, the interest and 
progress of agriculture would be more surely and permanently 
served, if its great patron Societies were to permit to their scien- 
tific officers a wider range of discretion, and more liberal means 
for the selection and carrying out of definite questions of research. 
Results of this kind promise, it is true, but little prospect of 
immediate and direct practical application, but by their aid the 
uncertain dictates, whether of common experience, theory, or 
speculation, may, ere long, be replaced by the unerring guidance 
of principles ; and then alone can it reasonably be anticipated 
that miscellaneous and departmental analyses may find their true 
interpretation, and acquire a due and practical value. 



nUMTKD BT 
■POTTttWOODE AND CO., KXW-flTMEET SQUARX 

LONDON 



REPORT 

UPON SOME EXPERIMENTS UNDERTAKEN AT THE 
SUGGESTION OF PROFESSOR LINDLEY, 

TO ASCEBTAIR TRC 

COMPARATIVE EVAPORATING PROPERTIES 



OF 



EVERGREEN AND DECIDUOUS TREElS. 



By J. B. LAWES, Esq., 

OF BOTHAM8TED. 



LONDON: 
PRINTED BY W. CLOWES AND SONS, STAMFORD STREET 

AND OHARINQ CROSS. 

1851. 



JUSPBINTED BY SP0TTI8W00DB k CO., NBW-STREBT SQUARE. 

1894. 



4 Evaporation of Evergreen and Deciduous Trees, 

escape of water except through the trees. The plants were placed 
in an open shed, protected from the rain, and were supplied with 
water from time to time as they seemed to require it; the 
weights were taken by means of the apparatus described in the 
* Journal of the Horticultural Society ' of January 1850. Upon 
referring to Table I. it will be seen that a considerable falling off 
in the water evaporated is ^apparent at the period when the oil- 
skin was put over the openings and the air perfectly excluded. 
Part of the pots were so covered on April 14th, and the remainder 
on April 24th ; it appears to me probable that the reduction in the 
water evaporated is not entirely due to the water being prevented 
from escaping through the hole in the lid, but that it is partly 
due to an injurious effect upon the plants themselves, some of 
them having evidently suffered. 

With the exception of the Ilex, which declined from the 
commencement, and appeared to be dead, or nearly so, in 
the spring, all the plants are alive at this time, but not equally- 
healthy. The Yew has been perfectly healthy all the year ; 
shoots about 2 inches long have been produced from each 
stem ; it is quite as vigorous as one exactly similar planted in 
the garden. Evergreen Berberry, perfectly healthy, lost all its 
leaves in the spring, and produced fresh ones quite equal to that 
in the garden. Portugal Laurel, about the same as when planted, 
has not grown. Common Laurel, a great many leaves fallen at 
various times, which have not been reproduced; the garden 
plant much healthier. Spruce Fir produced young shoots about 
2 inches long, which are now green, but the remainder of the 
plant is brown, and I should think would die if not removed. 
Holly very healthy, a little grown, quite equal to the garden 
plant. Larch grew well at first, but in the summer the leaves 
were covered with spots of turpentine, and the colour of the 
leaves was unhealthy; I should doubt whether it would live 
another year. Sycamore tolerably healthy, but some of the leaves 
mildewed. Oak and Ash about the same, tolerably healthy. 
Berberis D. healthy all the year. 

Table No. II., in which the amount of water evaporated is 
divided into periods of four months, shows very clearly the 
comparative characters of Evergreen and Deciduous trees. Of 
the six Evergreen plants, the amount of water evaporated during 
the first four months was 44 per cent, of that evaporated during 
the following four months ; while in the Deciduous plants it was 
only 14 per cent.: this would account for the large percentage 
of loss when evergreens are transplanted in winter. In Table 
IV., where the amount of water evaporated is divided into three 
portions, the comparative characters of the two descriptions of 
plant are still more clearly shown. 



Evaporation of Evergreen and Beciduoxis Trees, 



Table I. 

Loss of Water, obtained by Weighing varioos Plants during a Period of 
Twelve Months, — .Ictoal Results of Loss in Grains. 





Nnmber 


Nnmberof 


Loss 
per Dleoi. 


Mean Tem- 


Hygro- 
meter. 


Dfttaa. 


of 
Days. 


Grains 
ETapoiated. 


perature of 
Day ; Fahr. 




1 

SPRUCE FIR. 


t 






Dec. 22 t4) Jan. 3 


12 


4,620 


385*0 


30-60 


1-18 


Jan. 3 to Jan. 13 


10 


1,415 


141-5 


3215 


0-06 


Jan. 13 to Jan. 23 


10 


2,645 


264-5 


28-20 


0-86 


Jan. 23 to Feb. 3 


11 


2,320 


210-9 


3118 


0-24 


Feb. 3 to Feb. 13 


10 


3,195 


319-5 


40-96 


1-40 


Feb. 13 to Feb. 23 


10 


3,645 


864-5 


44-20 


2-00 


Feb. 23 to Mar. 5 


10 


2,660 


2660 


41-65 


1-60 


Mar. 5 to Mar. 15 


10 


3,140 


314-0 


39-80 


3-70 


Mar. 15 to Mar. 25 


10 


3,330 


3330 


36-35 


4-76 


Mar. 25 to Apr. 4 


10 


6,160 


6160 


40-40 


6-46 


Apr. 4 to Apr. 14 


10 


3,110 


311-0 


49-35 


2-03 


Apr. 14 to Apr. 24 


10 


2,505 


250-5 


47-75 


2-60 


Apr. 24 to May 4 


10 


3,295 


329-5 


46-60 


9-66 


May 4 to May 14 


10 


2,480 


2480 


47-40 


300 


May 14 to May 24 


10 


2,880 


288-0 


52-76 


4-30 


May 24 to June 3 


10 


4,550 


456-0 


56-30 


613 


Jnne 3 to June 13 


10 


5,620 


5520 


59-10 


8-80 


June 13 to June 23 


10 


8,800 


8800 


66-66 


9-86 


Jane23 to July 23 


30 


17,670 


5890 


61-96 


4-61 


July 23 to Aug. 22 


30 


11.300 


376-6 


62-13 


2-10 


Aug. 22 to Sept. 21 


30 


11,260 


376-3 


63-90 


4-97 


Sept. 21 to Oct. 21 


30 


11,680 


889-3 


49-21 


2-21 


Oct. 21 to Nov. 20 


30 


4,530 


161-0 


43-86 


1-18 


Nov. 20 to Dec. 31 

P 


41 
ORTUGi 


1,640 
KL LAIJ] 


40-0 
iUEL. 


38-67 


018 


Dec 22 to Jan. 3 


12 


3,960 


330 


30-50 


118 


Jan. 3 to Jan. 13 


10 


1,300 


130 


3215 


0-06 


Jan. 13 to Jan. 23 


10 


1,840 


184 


28-20 


0-86 


Jan. 23 to Feb. 3 


11 


1.760 


160' 


31-18 


0-24 


Feb. 3 to Feb. 13 


10 


3,550 


365 


40-95 


1-40 


Feb. 13 to Feb. 23 


10 


3,400 


340 


44-20 


200 


Feb. 23 to Mar. 5 


10 


8,010 


301 


41-65 


1-60 


Mar. 5 to Mar. 15 


10 


3,440 


344 


39-80 


3-70 


Mar. 15 to Mar. 25 


10 


5.190 


519 


36-36 


4-76 


Mar. 25 to Apr. 4 


10 


4,230 


423 


40-40 


5*46 


Apr. 4 to Apr. 14 


10 


4,740 


474 


49-35 


2-03 


Apr. 14 to Apr. 24 


10 


3,320 


332 


4776 


2-50 


Apr. 24 to May 4 


10 


3,900 


390 


46-60 


9-66 


May 4 to May 14 


10 


3,510 


351 


47-40 


300 


May 14 to May 24 


10 


5,080 


608 


52-76 


4-30 


May 24 to Jnne 3 


10 


8,640 


854 


66-30 


5-13 


June 3 to June 13 


10 


9,120 


912 


69-10 


8-80 


June 13 to Jnne 23 


10 


11,160 


1116 


56-56 


9-86 


June 23 to July 23 


30 


30,390 


1013 


61-96 


4-61 


July 23to Aug. 22 


30 


31,840 


1061-3 


6213 


210 


Aug. 22 to Sept 21 


30 


26,670 


889 


53-90 


4-97 


Sept. 21 to Oct. 21 


30 


18,520 


617-3 


49-21 


2-21 


Oct. 21 to Nov. 20 


30 


5,660 


188-7 


43-86 


118 


Nov. 20 to Dec. 31 


. 41 

1 


2,270 


65-3 


38-57 


018 



Evaporation of Everip'een and Beciduom Trees, 



Table I. — continued. 



Dates. 



Number 

of 
Days. 



Number of 

Grains 
Evaporated. 



Loss 
per Diem. 



EVERGREEN BERBERIS. 



Dec. 22 to Jan. 3 
Jan. 3 to Jan. 13 
Jan. 13 to Jan. 23 
Jan. 23 to Feb. 3 
Feb. 3 to Feb. 13 
Feb. 13 to Feb. 23 
Feb. 23 to Mar. 5 
Mar. 5 to Mar. 16 
Mar. 15 to Mar. 25 
Mar. 25 to Apr. 4 
Apr. 4 to Apr. 14 
Apr. 14 to Apr. 24 
Apr. 24 to May 4 
May 4 to May 14 
May 14 to May 24 
May 24 to June 3 
June 3 to June 13 
June 13 to June 23 
June 23 to July 23 
July 23 to Aug. 22 
Aug. 22 to Sept. 21 
Sept. 21 to Oct. 21 
Oct. 21 to Nov. 20 
Nov. 20 to Dec. 31 



Dec. 22 
Jan. 3 
Jan. 13 
Jan. 23 
Feb. 3 
Feb. 13 
Feb. 23 
Mar. 5 
Mar. 16 
Mar. 25 



4 

14 
24 

4 

14 
24 

3 



Apr. 
Apr. 
Apr. 
May 
May 
May 
June 
June 13 
June 23 
July 23 
Aug. 22 
Sept. 21 
Oct. 21 
Nov. 20 



to Jan. 
to Jan. 
to Jan. 
to Feb. 
to Feb. 
to Feb. 
to Mar. 
to Mar. 
to Mar. 
to Apr. 
to Apr. 
to Apr. 
to May 
to May 
to May 
to June 
to June 
to June 
to July 
to Aug. 
to Sept. 
to Oct. 
to Nov. 
to Dec. 



A ... 

13 ... 

23 ... 

u ... 

13 ... 

23 ... 
6 ... 

15 ... 

25 ... 

4 ... 

14 ... 

24 ... 
4 ... 

14 ... 

24 ... 

o ... 

13 ... 

23 ... 

23 ... 

22 ... 

21 ... 

21 ... 

20 ... 

31 ... 





12 




10 




10 




11 




10 




10 




10 




10 




10 




10 




10 




10 




10 




10 




10 




10 




10 




10 




30 




30 




30 




30 




30 




41 



1,810 

745 

810 

875 

1,860 

2,940 

1,670 

2,180 

3,320 

2,660 

2,620 

3,040 

2,330 

1,640 

2,870 

5,950 

9,020 

7,760 

31,160 

26,180 

22,510 

17,170 

5,640 

1,700 



YEW. 



12 
10 
10 
11 
10 
10 
10 
10 
10 
10 
10 
10 
10 
10 
10 
10 
10 
10 
30 
30 
30 
30 
30 
41 



3,720 

1,795 

1,985 

2,420 

3,650 

4,630 

4,300 

4,800 

5,370 

7,480 

7,090 

8,160 

8,700 

4,450 

7,020 

9,750 

8,605 

9,556 

30,370 

24.285 

21,845 

20,060 

6,590 

730 



150-8 
74-6 
810 
79-5 

I860 

294 

167 

218 

832 

266 

262 

304 

233 

164 

287 

595 

902 

775 
1038-6 

872-7 

750-3 

572-3 

184-7 
41-5 



3100 
179-5 
198-5 
220 
365 
463 
430 
480 
537 
748 
709 
816 
870 
445 
702 
975 
850-5 
955-5 
1012-3 
809-6 
728-2 
668-6 
219-6 
17-8 



Muan Tem- 
perature of 
Day ; Fahr. 



Hyin-o- 
meter. 



30-60 


1-18 


3216 


0-O6 


28-20 


0-86 


3118 


0-24 


40-95 


1-40 


44-20 


20O 


41-65 


1-60 


39-80 


3-70 


35-35 


4-76 


40-40 


6-46 


49-35 


2-03 


47-75 


2'50 


45-60 


9-66 


47-40 


8-0O 


52-75 


4-30 


66-30 


5-13 


5910 


8-80 


56-55 


9-86 


61-96 


4-61 


6213 


210 


53-90 


4-97 


49-21 


2-21 


43-86 


118 


38-57 


0-18 



30-60 
32-15 
28-20 
3118 
40-95 
44-20 
41-65 
39-80 
35-35 
40-40 
49-35 
47-76 
45-60 
47-40 
52-75 
56-30 
5910 
66-55 
61-96 
62-13 
63-90 
49-21 
43-86 
38-57 



1-18 
0-06 
0-86 
0-24 
1-40 
200 
1-60 
3-70 
4-76 
5-46 
203 
2-50 
9-66 
3-00 
4-30 
G-13 
8-80 
9-86 
4-61 
210 
4-97 
2-21 
1-18 
018 



Evap<yratum of Evergreen and Dedduom Trees, 



Tablb L— con^mutfcJ. 



Dec. 22 to Jan. 3 
Jan. 3 to Jan. 13 
Jan. 13 to Jan. 23 
Jan. 23 to Feb. 3 
Feb. 3 to Feb. 13 
Feb. 13 to Feb. 23 
Feb. 23 to Mar. 5 
Mar. 5 to Mar. 15 
Uar. 16 to Mar. 26 
Uar. 25 to Apr. i 
Apr. 4 to Apr. 14 
Apr. 14 to Apr. 24 
Apr. 24 to May 4 
Hay 4 to Hay 14 
Hay 14 to Hay 24 
Hay 24 to Jane 3 
June 3 to June 13 
June 13 to Jane 23 
June 23 to July 23 
July 23 to Aug. 22 
Aug. 22 to Sept. 21 
Sept. 21 to Oct. 21 
Oct. 21 to Nov. 20 
Not. 20 to Dec. 31 



Dec 

Jan. 

Jan. 

Jan. 

Feb. 

Feb. 

FeU 

Har. 

Har. 

Har. 

Apr. 

Apr. 

Apr. 

Hay 

Hay 

Hay 

Jone 

Jane 



22 to 
3to 

13 to 

23 to 
3to 

13 to 

23 to 
5to 

16 to 

25 to 

4to 

14 to 

24 to 
4to 

14 to 

24 to 

3 to 

13 to 



Jane 23 to 
July 23 to 
Aug. 22 to 
Sept. 21 to 
Oct. 21 to 
NoY, 20 to 



Jan. 3 
Jan. 13 
Jan. 23 
Feb. 3 
Feb. 13 
Feb. 23 
Mar. 5 
Mar. 16 
Mar. 26 
Apr. 4 
Apr. 14 
Apr. 24 
May 4 
May 14 
May 24 
June 3 
June 13 
Jane 23 
July 23 
Aag.22 
Sept. 21 
Oct 21 
Nov. 20 
Dec. 31 



Number 

of 

D»y8. 



Nomber of 

drains 
ETaporated. 



Loss 
per Diem. 



Mean Tern- 
peratoreof 
Day; Fahr. 



HOLLY. 





12 


1,800 


1500 


30'50 




10 


610 


61-0 


3216 




10 


846 


84-5 


28-20 




11 


1,126 


102*2 


8118 




10 


2,070 


207 


40-95 




10 


2,760 


276 


44-20 




10 


1.820 


182 


41*65 




10 


2,640 


264 


39-80 




10 


3,200 


320 


85-36 




10 


2,590 


269 


40-40 




10 


2,620 


262 


49-35 




10 


1,700 


170 


47-76 




10 


2,300 


230 


45-60 




10 


1,400 


140 


47-40 




10 


2,130 


213 


52-75 




10 


8,226 


322-5 


56-30 




10 


2,916 


291-5 


59-10 




10 


2,370 


237 


56-55 




30 


9,140 


304-7 


61*96 




30 


10,100 


%^e 


6213 




30 


7,150 


238-3 


63-90 




30 


7,820 


260-6 


49-21 




30 


3,780 


126 


43-86 




41 


1,500 


37-6 


38-57 



COMMON LAUREL. 





12 


2,718 


226*6 


30*50 




10 


1,802 


180-2 


32-15 




10 


1,895 


189-5 


28-20 




11 


2,415 


219-5 


31-18 




10 


3,716 


371-5 


40-95 




10 


3,896 


389-5 


44-20 




10 


3,250 


326 


41-65 




10 


4,270 


427 


39-80 




10 


4,910 


491 


35*35 




10 


4,890 


489 


40-40 




10 


5,460 


646 


49*35 




10 


4,220 


422 


47-75 




10 


7.160 


716 


46-60 




10 


8,240 


824 


47-40 




10 


12.375 


1237-5 


62-76 




10 


13,796 


1379-6 


56-30 




10 


12,590 


1259 


69-10 




10 


11,690 


1159 


56-55 




30 


37,460 


1248*3 


61-96 




30 


26,640 


888 


6213 




30 


22,940 


764*6 


53-90 




30 


16,520 


5506 


4921 




30 


6,110 


203-6 


43-86 




41 


2,030 


49-5 


38-57 



Hygro- 
meter. 



1*18 
0*06 
0-86 
0-24 
1-40 
200 
1*60 
3-70 
4-76 
6-46 
2-03 
2-50 
9*66 
3*00 
4-30 
6*13 
8-80 
9-86 
4*61 
210 
4-97 
2*21 
118 
018 



118 
006 
0-86 
0-24 
1-40 
2-00 
1-60 
3-70 
4-76 
6-46 
203 
2*50 
9*66 
300 
4*30 
5-13 
8*80 
9-86 
4-61 
2*10 
4*97 
2-21 
118 
018 



8 



Evaporation of Evergreen and Deciduous Trees, 



Table I. — continued. 





Number 


Number of 


Loes 
per Diem. 


Mean Tem- 


^yg^^- 
metcr. 


Dates. 


of 
Days. 


Qrains 
Evaporated, 


perature of 
Day; Fkhr. 


1 i 1 
ILEX, 








Dec. 22 to Jan. H ... .. 


12 


980 


M-7 


80-50 


1-13 


Jan. 3 to Jan. IS 


10 


370 


37 


82-15 


0-06 


Jan. 13 to Jan. 28 


10 


820 


82 


28-20 


0-86 


Jan. 23 to Feb. 8 


11 


580 


527 


8118 


0^24 


Feb. 3 to Feb. 18 


10 


240 


24 


40-95 


1-40 


Feb. 13 to Feb. 28 


10 


1,.%0 


136 


44-20 


2-00 


Feb. 23 to Mar. 6 


10 


580 


58 


41-61^ 


1-60 


Mar. 6 to Mar. 15 


10 


1,130 


113 


8980 


3-70 


Mar. 15 to Mar. 26 ... .. 


, 10 


2,600 


260 


35-36 


4-76 


Mar. 25 to Apr, 4 .., ... 


10 


l/)20 


102 


40-40 


6-45 


Apr. 4 to Apr. 14 ..* .. 


10 


1,130 


113 


49-36 


203 


Apr. 14 to Apr. 24 


, 10 


160 


16^ 


47-75 


2-50 


Apr. 24 to May 4 


, 10 


830 


83 


46-60 


9-66 


May 4 to May 14 ... 




10 


240 


24 


47-40 


300 


May 14 to May 24 ... 




10 


260 


26 


52-76 


4-30 


May 24 to Jane 3 ... 




10 


650 


65 


66-80 


6-13 


June 3 to June 13 ... 




10 


234 


23-4 


6910 


8-80 


June 13 to Jane 23 ... 




10 


296 


29*6 


56-56 


»-86 


June 23 to July 23 ... 




80 


480 


16 


61-96 


4-61 


July 23 to Aug. 22 ... 




30 


600 


20 


6213 


210 


Aug. 22 to Sept, 21 ... 




30 


180 


6 


68-90 


4-97 


Sept. 21 to Oct, 21 ... 




30 


800 


26-6 


49-21 


2-21 


Oct. 21 to Nov, 20 ... 




30 


140 


4-6 


43-86 


118 


Nov. 20 to Dec. 31 ... 




, 41 


860 


8-8 


38-67 


018 


L 


ARCH, 








Dec. 22 to Jan. 3 ... .. 


12 


640 


53-3 


30-50 


118 


Jan. 3 to Jan. 13 .. 




. 10 


100 


10 


32-15 


0^6 


Jan. 13 to Jan. 23 ... 




10 


125 


12-6 


28-20 


0-86 


Jan. 23 to Feb. 3 ... 




11 


215 


19-5 


81-18 


0-24 


Feb. 3 to Feb. 13 ... 




10 


610 


61 


40-96 


1-40 


Feb. 13 to Feb. 23 ... 




10 


1,070 


107 


44-20 


2-00 


Feb. 23 to Mar. 5 .. 




10 


450 


45 


41-65 


1-60 


Mar. 5 to Mar. 15 .. 




10 


1,040 


104 


89-80 


3-70 


Mar. 15 to Mar. 25 ... 




10 


2,040 


204 


35-36 


4-76 


Mar. 25 to Apr. 4 .. 




10 


1,440 


144 


40-40 


6-46 


Apr. 4 to Apr. 14 ... 




10 


1,580 


158 


49-36 


2-08 


Apr. 14 to Apr. 24 ... 




10 


2,260 


226 


47-75 


2-60 


Apr. 24 to May 4 ... 




10 


960 


96 


45-60 


9-66 


May 4 to May 14 ... 




10 


720 


72 


47-40 


30O 


May 14 to May 24 ... 




10 


1,270 


127 


52-75 


4-30 


May 24 to June 3 ... 




10 


1,680 


168 


66-80 


6-13 


June 3 to June 13 ... 




10 


2,160 


216 


6910 


8-80 


June 13 to June 23 ... 




10 


3.000 


300 


66-65 


9-86 


June 23 to July 23 .. 




. 30 


16,690 


556-3 


61-96 


4-61 


July 23 to Aug. 22 ... 




30 


26,050 


868-3 


6213 


2-10 


Aug. 22 to Sept. 21 .. 




30 


24,850 


828-3 


53-90 


4-97 


Sept. 21 to Oct. 21 ... 




20 


21,680 


719-3 


49-21 


2-21 


Oct. 21 to Nov. 20 .. 




. 30 


3,.S20 


110-6 


, 43-86 


118 


Nov. 20 to Dec. 31 .. 




. 41 


450 


110 


38-57 


0-18 



Evajxn-ation of Evergreen and Deciduous Trees, 



9 



Table I. — continued. 






Dates. 


Nnmber 
of 


Nnmber of 
Grains 


Loss per 


Mean Tcm- 
pemtureof 


Hygro- 




D»yi. 


ETapormted. 


JL/lCIll. 


Day; Fahr. 


MAA^WM • 






OAK. 








Dec. 22 to Jan. 8 


12 


660 


65 


30-50 


1-18 


Jan. 3 to Jan. 13 


10 


160 


15 


3215 


0-06 


Jan. 13 to Jan. 23 


10 


126 


12-5 


28-20 


0-86 


Jan. 23 to Feb. 3 


11 


166 


141 


3118 


0-24 


Feb. 3 to Feb. 13 


10 


190 


19 


40*95 


1-40 


Feb. 13toFeb. 23 


10 


200 


20 


44*20 


200 


Feb. 23 to Mar. 5 


10 


390 


39 


4165 


1-60 


Mar. 6 to Mar. 15 


10 


790 


79 


39-80 


3-70 


Mar. 15 to Mar. 26 


10 


2,110 


211 


35-85 


4-76 


Mar. 25 to Apr. i 


10 


1,290 


129 


40-40 


6-46 


Apr. 4 to Apr. 14 


10 


900 


90 


49-35 


2-03 


Apr. 14 to Apr. 24 


10 


1,660 


165 


47-76 


2-60 


Apr. 24 to May 4 


10 


10 


1 


45-60 


9-66 


May 4 to May 14 


10 


210 


21 


47-40 


3-00 


May 14 to May 24 


10 


270 


27 


52-75 


4-30 


May 24 to Jane 3 


10 


1,220 


122 


56-30 


513 


Jane 3toJnnel3 


10 


1,690 


159 


69-10 


8-80 


Jane 13 to Jane 23 


10 


2,390 


239 


66-55 


9*86 


Jane 23 to Jaly 23 


30 


11,710 


390-3 


61-96 


4-61 


Joly 23 to Aag. 22 


30 


17,660 


588-3 


62-13 


2-10 


Aog. 22 to Sept. 21 


30 


17,730 


591 


53*90 


4-97 


Sept. 21 to Oct. 21 


30 


13,950 


465 


49-21 


2-21 


Oct. 21 to Nov. 20 


30 


4,460 


148-6 


43-86 


1-18 


Nov. 20 to Dec. 31 


41 


890 


21-7 


38-57 


0-18 


DEC 


JIDUOl 


JS BKR6] 


SKIS. 






Dec. 22 to Jan. 3 


12 


820 


68-3 


30-50 


MS 


Jan. 3 to Jan. 13 


10 


165 


15-6 


3216 


0-06 


Jan. 13 to Jan. 23 


10 


190 


19 


28-20 


0-86 


Jan. 23 to Feb. 3 


11 


185 


16-8 


31-18 


24 


Feb. 3 to Feb. 13 


10 


630 


63 


4095 


1-40 


Feb. 13 to Feb. 23 


10 


826 


82-5 


44*20 


200 


Feb. 23 to Mar. 5 


10 


376 


37-5 


41*65 


1-60 


Mar. 5 to Mar. 16 


10 


1,240 


124 


39-80 


3-70 


Mar. 16 to Mar. 25 


10 


2,460 


246 


36 35 


4-76 


Mar. 25 to Apr. 4 


10 


3,360 


335 


40-40 


5-46 


Apr. 4 to Apr. 14 


10 


1,080 


108 


49-35 


203 


Apr. 14 to Apr. 24 


10 


630 


63 


47-75 


2-50 


Apr. 24 to May 4 


10 


2,370 


237 


45-60 


9-66 


May 4 to May 14 


10 


3,180 


318 


47-40 


300 


May 14 to May 24 


10 


6,896 


589-5 


62-76 


4-30 


May 24 to Jane 3 


10 


9,105 


910-5 


66-30 


6-13 


Jane 3 to Jane 13 


10 


9,614 


951-4 


59-10 


8-80 


June 13 to June 23 


10 


10.236 


1023-6 


66*55 


9-86 


June 23 to Jaly 23 


30 


31,»70 


1062-3 


61-96 


4-61 


Jaly 23 to Aag. 22 


30 


30,020 


1000-6 


6213 


2-10 


Ang. 22 to Sept.21 


30 


32,990 


10996 


63-90 


4-97 


Sept. 21 to Oct. 21 


30 


28,770 


959 


49-21 


2-21 


Oct. 21 to Nov. 20 


30 


3,770 


126-6 


43-86 


1-18 


Nov. 20 to Dec. 31 


41 


550 


13-4 


88*67 


0-18 



10 



Evaporation of Evergreen a/nd Deciduous Trees, 



Table 1.— continued. 



Dates. 



Dec 22 to Jan. 3 
Jan. 3 to Jan. 13 
Jan. 13 to Jan. 23 
Jan. 23 to Feb. 3 
Feb. 3 to Feb. 13 
Feb. 13 to Feb. 23 
Feb. 23 to Mar. 6 
Mar. 5 to Mar. 16 
Mar. 16 to Mar. 26 
Mar. 26 to Apr. 4 
Apr. 4 to Apr. 14 
Apr. 14 to Apr. 24 
Apr. 24 to May 4 
May 4 to May 14 
May 14 to May 24 
May 24 to June 3 
Jane 3 to June 13 
June 13 to June 23 
June 23 to July 23 
July 23 to Aug. 22 
Aug. 22 to Sept. 21 
Sept. 21 to Oct. 21 
Oct. 21 to Nov 20 
Nov. 20 to Dec. 31 



Number 

of 

Dayi. 



Nomber of 

Grains 
Evaporated. 



Loss per 
Diem. 



Mean Tem> 
peratureof 
Day ; Fahr. 



Hygio- 





12 




10 




10 




11 




10 




10 




10 




10 




10 




10 




10 




10 




10 




10 




10 




10 




10 




10 




30 




30 




30 




30 




30 




41 



ASH. 

1,290 

110 

100 

100 

690 

390 

280 

830 

1,830 

1,290 

660 

340 

346 

636 

1,660 

6,660 

7,860 

10,360 

30,210 

26,600 

21,600 

2,400 

840 

720 



SYCAMORE. 



107-6 

11 

10 
91 

69 

39 

28 

83 
163 
129 

66 

34 

34-6 

63-6 
166 
666 
786 
1036 
1007 
860 
716-6 

80 

28 

17-6 



80-60 
3216 
28*20 
31-18 
40-96 
44-20 
41-66 
39-80 
35-36 
40-40 
49-36 
47-76 
46-60 
47-40 
62-76 
66-30 
6910 
66-66 
61-96 
6213 
63-90 
49-21 
43-86 
38-67 



118 

0-06 

0-86 

0-24 

1-40 

200 

1-60 

3-70 

4-76 

5-46 

2*03 

2-60 

9'66 

3-00 

4-30 

ol3 

8-80 

9-86 

4-61 

2-10 

4-97 

2-21 

1*18 

018 



Dec. 22 to Jan. 3 


12 


620 


51-7 


30-60 


1-18 


Jan. 3 to Jan. 13 


10 


240 


24 


82-16 


006 


Jan. 13 to Jan. 23 


10 


140 


14 


28-20 


0-86 


Jan. 23 to Feb. 3 


11 


160 


14-5 


31-18 


0-24 


Feb. 3 to Feb. 13 


10 


260 


25 


40*96 


1-40 


Feb. 13 to Feb. 23 


10 


610 


61 


44-20 


2-00 


Feb. 23 to Mar. 6 


10 


890 


89 


41-66 


1-60 


Mar. 6 to Mar. 16 


10 


1,280 


128 


39-80 


3-70 


Mar. 16 to Mar. 25 


10 


2,380 


238 


36*36 


4*76 


Mar. 25 to Apr. 4 


10 


1,430 


143 


40*40 


6-46 


Apr. 4 to Apr. 14 


10 


1,660 


166 


49*36 


203 


Apr. 14 to Apr. 24 


10 


80 


8 


47-76 


260 


Apr. 24 to May 4 


10 


200 


20 


46*60 


9-66 


May 4 to May 14 


10 


210 


21 


47-40 


300 


May 14 to May 24 


10 


720 


72 


62-75 


4-30 


May 24 to June 3 


10 


4,420 


442 


66-30 


5-13 


June 3 to June 13 


10 


6,360 


636 


69-10 


8-80 


June 13 to June 23 


10 


8,070 


807 


56-55 


9-86 


June23 to July 23 


30 


27,410 


913-6 


61-96 


4-61 


July 23 to Aug. 22 


30 


27,990 


933 


6213 


2-10 


Aug. 22 to Sept. 21 


30 


26,890 


896-3 


63-90 


4-97 


Kept. 21 to Oct. 21 


30 


19,150 


638-3 


49-21 


2*21 


Oct. 21 to Nov. 20 


30 


1,680 


62-7 


43-86 


M8 


Nov. 20 to Dec. 31 


41 


680 


16 6 


38-57 


0-18 



Evajporaivm of Everg^'een and Deciduous Trees, 



11 



Tablb ]I. 
Watkb Evapokatbd Id periods of Four Months, by various Plants — Grains 





December 23 


April 24 


August 23 




to 


to 


to 




April 34. 


August 23. 
66,696 


December 31. 


Sprace Fir 


38,726 


29,1 10 


Portugal Laurel 


39,740 


104,040 


63,022 


Evergreen Berberis ... 


24,630 


86,910 


46,920 


JL %?1V ••■ ••• ••• •*• 


66,400 


102,636 


49,226 


Holly 


23,780 


33,680 


20,260 


Common Laurel 


43,440 


129,840 


47,600 


^^w2 ••• ••• ••• ••• 


10,970 


3,090 


1.480 


JjAXvO •«• ••• ••« *•■ 


11,670 


62,630 


60,200 


V/nK ••• ••• >•• ••• 


8,610 


36,060 


37,030 


Deciduous Berbeiis ... 


11,740 


102,190 


66,080 


aXoXI ••• ••• ••• ••• 


7,900 


81,920 


25,470 


Sycamore 


9,730 


75,380 


48,300 



Tablb III. 
Wateb Evaporated in Twelve Months, by varions Plants— Grains. 







Water 


Water 
obtained from 










supplied to 


Total 






8pmce Fir 


8olL 


Soil. 


Evaporated. 






91,400 


33,030 


124,430 




1 


Portugal Laurel 


166,400 


40,602 


196,902 






Eveiigreen Berberis ... 


123,900 


33,460 


167,360 






X C^r •■• ••« ••• ••« 


171,400 


36,860 


207,260 






Holly 


61,400 


16,210 


77,610 






Common Laurel 


181,400 


39,480 


220,880 






IIpt 

AACA ••« ••• ■•• ■«• 


13,400 


2,100 


16,540 






Larch 


'■«7.400 


26,900 


114,300 






VxOBk ••• ••• ••• ••• 


57.400 


23,190 


80,590 






Deciduous Berberis . . . 


137.400 


42,610 


180,010 






^aOU •«• ••• t»a ••■ 


102,400 


12,890 


116,290 






Sycamore 


97,400 


36,010 


133,410 





Table IV. 

Table showing the Periods of the year in which Evergreen and Deciduous 

Plants Evaporate 100 Parts of Water. 



Four months to April 24 

August 22 .. 
December 31 



»» 



»» 



Evergreen. 
.. 23 
.. 62J 
.. 24*- 

100 



Deciduous. 
8 
56 
36 

100 



12 Evaporation of Evergreen and Deciduous Trees. 

Note upon the Preceding Experiments. 

The evaporating power of the leaves is one of the most im- 
portant properties of plants, for on the healthy performance of 
this function depend not merely the vigour and development of 
the plant, but also, indeed, its very existence. Every new fact, 
therefore, which in any way tends to elucidate the chemical or 
physiological nature of the leaves, or which throws lij^ht upon 
the mode in which they act, and the effects produced by the 
various agents to the influence of which they are naturally sub- 
ject, is highly interesting. The preceding experiments were 
undertaken with a view to ascertain the ratio which exists 
between the evaporating power of different leaves, contrasting 
tosrether in particular those of Everfireens and those of Decidnons 
plants. Before making one or two*^remarks which these experi- 
ments suggest, it will, perhaps, not be out of place to say a 
few words respecting some former investigations on the same 
subject. 

It is more than a hundred and fifty years since Dr. Woodward 
published, in the twentieth volume of the * Philosophical Trans- 
actions of the Boyal Society,' an account of some experiments on 
vegetation, having for their especial object to determine the eva- 
porating power of the leaves. These experiments were curious, 
and excited a good deal of interest at the time the results were 
published. Some of the conclusions drawn from them were 
tolerably accurate, but from the vague and uncertain views 
which were then generally entertained respecting the growth 
and nourishment of plants, the very facts themselves became, to 
a very great extent, mystified and confused, so that their prac- 
tical value was greatly diminished. 

Dr. Woodward's experiments were made with weighed bottles 
of water, having a piece of parchment tied over their mouths, in 
which a small aperture was made, just sufficient to admit the 
steia of a plant, but not so small as to confine or impede its 
growth. As the water evaporated, fresh was added from time to 
time, a register being kept of the quantity added, as well as of 
that which was lost by evaporation. The plants were placed 
side by side in a window, where they were equally exposed to 
sunshine ; and the experiment was continued from the 20th of 
July, 1691, to the 5th of October in the same year. The 
following was the result of one of these comparative experi- 
ments : — 



Evaporalion of Evergreen and Deciduous Trees. 



13 



Spearmint, in spring water ... 

• Ditto, in rain water 

j Ditto, in Thames water 

I Nightshade, in spring water. . . 

I Lathjris, in spring water ... 



Orlfrinal 


Final 


Water 


Weight. 


Weight. 


Evaporated. 


Grains. 


Grains. 


Grains. 


27 


42 


2558 


28 


45 


3004 


28 


54 


2493 


49 


106 


3708 


98 


101 


2501 



Proceeding to compare together the increase in weight of the 
plant with the quantity of water it had given off, Dr. Woodward 
showed that in the case of the three plants of Spearmint, it was 
respectively as 1 to 170, to 171, and to 95 ; whilst in the instance 
of Uie Nightshade it was as 1 to 65, and in that of the Lathyris 
as 1 to 714. It is evident, however, that from such experiments 
no very satisfactory or accurate conclusion could well be drawn ; 
they were repeated and varied in different ways, and similar 
results were obtained. One of the most curious of these experi- 
ments was an attempt to ascertain more exactly the precise effect 
of different kinds of water on the growth and evaporating power 
of the same plant ; in this case six plants of Spearmint were 
suffered to grow in weighed bottles of water for eight weeks ; the 
results were as follows : — 



Spearmint. 



1. In Hyde Park water 

«« A^XvtA/ ••• ■•* ••• ••• «•• ••• 

3. Ditto, with 4 an oz. of soil 

4. Ditto, with 4 an oz. of garden soil 

5. Distilled water 

& Hyde Park water, concentrated \ 

by evaporation j 



Original 
Weight. 


Tncrease. 


Water 
Evaporated. 


Grains. 


Grains. 


Grainn. 


127 


128 


14,190 


110 


139 


13,140 


76 


168 


10,731 


92 


284 


14.950 


114 


41 


8,803 


81 


94 


4,344 



Ratio of 

Incrpa.«4e to 

Evaporation. 



1 to 110 
1 to 94 
1 to 63 
1 to £2 
1 to 214 

1 to 46 



It was the common belief of many naturalists at the time that 
the increase in weight of plants was in direct proportion to the 
quantity of water which passed through them, or rather to the 
proportion of it which became fixed in their organs in the process 
of being absorbed by the roots and given off by the leaves. In 
the experiments ju^t mentioned, the last plant increased most in 
proportion to the quantity of water evaporated, but the fourth 
was the one which grew most luxuriantly, and it was also the 
one which absorbed the largest quantity of water in proportion 
to its weight. The plant fed with distilled water grew least of 
all, whilst that fed with spring water containing a portion of 
garden soil was by far the most flourishing. 



14 



Evapm^atioii of Evergreen and Deciduous Trees, 



These experiments of Woodward led Dr. Stephen Hales to 
make a number of curious and interesting observations on the 
evaporating power of the leaves of plants, which he published in 
1727, in the first volume of his celebrated 'Statical Essays/ 
Those which more immediately relate to the present subject will 
be found in the first chapter, **on the quantity of moisture 
imbibed and perspired by plants and trees." Hales*s most cele- 
brated experiment was made in 1724 with a healthy full-grown 
Sunflower, more than a yard high, and which had been purposely 
planted when young in a suitable flowerpot. The mode in which 
the experiment was conducted is best given in his own words : — 
" I covered the pot with a plate of thin milled lead, and cemented 
all the joints fast, so that no vapour could pass, but only air, 
through a small glass tube, 9 inches long, which was fixed pur- 
posely near the stem of the plant, to make a free communication 
with the outward air and that under the leaden plate. I cemented 
also another short glass tube into the plate, 2 inches long, and 
1 inch in diameter. Through this tube I watered the plant, and 
then stopped it up with a cork ; I also stopped up the hole at 
the bottom of the pot with a cork." 

Matters being thus arranged, the plant received a weighed 
supply of water, and being itself weighed twice a day for a fort- 
night, the rate of evaporation was easily observed. By another 
comparative experiment Dr. Hales ascertained the qucuitity of 
water evaporated every day by the porous earthen pot, and sub- 
tracted it from the whole daily loss sustained by the Sunflower. 
The result showed that on an average the plant evaporated 20 
ounces, or 34 cubic inches of water, in a twelve hours' day ; the 
maximum proportion being 30 ounces. This was certainly a 
very interesting and remarkable experiment, and it was rendered 
all the more so by the careful and minute details which accom- 
panied its publication ; including the bulk and length of the 
roots, and the exact size of the leaves. Hales also measured the 
rate of evaporation of a Cabbage, a Vine, a young Apple-tree, and 
a Lemon-tree. The result of these experiments is expressed in 
the following table : — 



Sunflower 
Cabbage ... 
Vine 

Apple-tree 
Lemon-tree 



Entire 

Surface of 

Leaves. 



Square inches. 
6616 
2736 
1820 
1689 
2657 



Water 
Perspired In 
13 hours. 



Ounces. 
20 
19 

5i 
9 



Ratio of 

Evaporation 

to Surface 

of Plant. 



T 



Tp 



Evaporatimi of Evergreen and Deciduous Trees. 15 

The practical conclusion drawn from these experiments was, 
that the Cabbage evaporated the greatest quantity of water, and 
the Lemon-tree the least. On repeating it with other plants Dr. 
Hales found that in all cases evergreens perspired less than those 
plants which shed their leaves in the winter, a fact which he 
endeavoured to explain by observing, that '' as they perspire less, 
so they are better able to survive the winter's cold." At the 
same time that he made these experiments he also made a number 
of other highly interesting ones, on the force with which plants 
absorb water, and many similar points connected with this part 
of their economy. 

A third series of experiments was made by Mr. Miller in 
1726, at the Chelsea Botanic Garden, at the suggestion of Dr. 
Hales, in which the subjects of experiment were a Musa, an Aloe, 
and an Apple-tree. The plants were grown in glazed earthen- 
ware pots, made without any holes at the bottom, so that there 
was no need to make any correction for the water lost by eva- 
poration ; the plants were weighed three times a day for some 
weeks, and the thermometer was noted at each weighing. The 
chief facta observed were, that the plants perspired more in the 
morning than in the afternoon ; that they very often absorbed 
moisture by the leaves during the night ; and that the proportion 
perspired was generally in direct proportion to the temperature 
of the day. 

These simple experiments are, all of them, perfectly satis- 
factory, and, as far as they go, are no doubt quite trustworthy. 
It is remarkable that during the last one hundred and thirty years 
hardly a single new fact of much importance has been added to 
this department of vegetable physiology, and that our knowledge 
of this important branch of the economy of vegetation is very 
little extended beyond what it was at the time of Hales. One 
reason of this certainly is, that the observers who followed him 
began to refine upon the simple mode of experimenting which 
he employed, and introduced complicated and unnatural forms of 
experiment, the results of which are, for the most part, of but 
little value. Thus the numerous and laborious experiments of 
Bonnet, undertaken chiefly at the suggestion of Calandrini, to 
ascertain the relative power of absorbing moisture by the superior 
and inferior surfaces of the leaf, were far from satisfactory ; be- 
cause, though his object was to measure the power of absorbing 
aqueous vapour, his experiments in fact all had reference to a dif- 
ferent point, namely, the power of the leaves to absorb water, when 
placed in contact with it, by the upper or lower surface. The 
jezperiments of Bonnet, even on the direct absorption of water, 
do not really give a true indication of the evaporating power of 
the leaves, because they were made on single leaves and not on 



16 Evaporation of Evergreen and Becidvjous Trees, 

entire plants ; they consequently did not fairly represent the sound 
and perfect leaves of a growing plant. 

The very numerous series of experiments, on the evaporation 
from leaves, detailed in the preceding pages, are highly valuable, 
because they extend over a considerable period of time, and 
therefore are less under the influence of the various interfering 
causes which generally introduce errors into such investigations. 
At the same time, however, they are by no means unexception- 
able, for there are several matters connected with them which are 
open to doubt and uncertainty. The first great condition of all 
«uch experiments in every case is, that the plants must be brought 
into a healthy condition at the commeRcement of the experiment, 
and kept in a healthy state all through it ; if the plant is ren- 
dered sickly and unhealthy by the conditions of the experiment, 
it is plain that, the circumstances being forced and unnataral, 
they cannot be expected to yield satisfactory results. Now, in 
the preceding experiments, the plants were unquestionably in- 
jured by the treatment they received, and, what is still worse, 
they were injured to an unequal extent, some of them being 
rendered far more sickly than the others. If means cannot be 
devised to prevent the evaporation of moisture from the surface 
of the soil without tying bandages round the stem, it is far better 
to calculate the amount of water thus lost, as Hales did, and 
flubtract it from the total loss at each weighing. If all the other 
circumstances are perfectly similar, this loss would not vary 
much ; it would be pretty nearly constant with each of the dif- 
ferent plants. It is also to be remarked, that in thus absolutely 
preventing all evaporation from the enclosed soil, excepting that 
which took place through the leaves of the plant, the soil was 
altogether cut off from contact with tbe external air, and thus 
another, and by no means unimportant, condition was intro- 
duced. 

In experiments of this sort it is very desirable not to com- 
mence them the very day the plants have been transplanted ; 
some little time should be allowed to elapse before the experi- 
ment is begun, so that the plants may become accustomed to the 
new conditions under which they are placed ; and in every case 
"where possible two or three similar plants should be tak^a for 
each experiment, instead of single ones. 

For tlie most part the experimental results are pretty nearly 
-what might have been expected, though of course there are 
exceptions and irregularities, which must be attributed to special 
interfering causes. There would seem to be a remarkable differ- 
ence between the several plants, as regaids the relation existing 
between the temperature and the rate of evaporation,independent]y 
of the dryness or moisture of the air. On comparing the tables 



Evaporaiion of Evergreen and Deciduous Trees, 1 7 

together, it will be found that in the case of the Portugal Laurel, 
Holly, Larch, and Sycamore, the maximum evaporation occurs at 
the same time as the maximum of temperature, namely, between 
the 23rd of July and the 22nd of August. This, however, is 
not the case with the other plants. In the case of the Oak, and 
the Deciduous Berberis, the maximum evaporation occurs after 
the greatest heat ; the greatest quantity of water being evaporated 
between the 22nd of August and the 21st of September, though 
the average temperature then was more than 8° lower than it had 
been during the previous four weeks. Exactly the reverse is the 
case with the remaining plants, for the maximum evaporation 
with the Spruce-Fir, Evergreen Berberis, Yew, Laurel, and Ash, in 
each instance preceded the maximum of heat. On i*efeiTing to 
the table showing the evaporation from the Evergreen Berberis, it 
will be found that from the 23rd of June to the 23rd of July, 
when the average temperature was below 62°, the daily loss of 
water was 1038 grains, whilst in the foUov^g month, though the 
thermometer was then above 62°, the daily evaporation was only 
872 grains. A similar eflfect may be observed with regard to the 
Yew. In July, with a temperature below 62°, the daily loss was 
1012 grains; in August, with an average temperature above 62°, 
the daily evaporation was only 809 grains. It is evident, there- 
fore, from these experiments, that evaporation is not a mere 
index of temperature, but that it depends on vitality, influenced 
by heat, light, and other causes. 



mCCTED EY 
■rOTTSn'OODK AND CO., KKW-STJUEKI' 6QUA3B 

LONDOX 

o 






OK 



AGRICULTURAL CHEMISTRY, 



ESPECIALLT IN RELATION TO THE 



MINERAL THEORY OF BARON LIEBIG. 



By J. B. LAWES, 

OF R0THAM8TED, 

And DR. J. H. GILBERT. 



LONDON: 

PRINTED BY W. CLOWES AND SONS, STAMFORD STREET. 



1651. 



REPRINTED BY SPOTTISWOODE & CO., NEWSTREET SQUARE. 

1895. 



FBOBC THE 
JOURNAL OF THE ROTAL AQRICULTURAL SOCIETY OF ENGLAND, 

VOL. Xn., PART L 



i 



i 

i 



ON 



AGRICULTUEAL CHEMISTRY. 



It was nnder the auspices of the British Association that Pro- 
fessor Liebig in the year 1840 first promulgated his views on 
the subject of Agricultural Chemistry ; and however much some 
may be disposed to differ from him in opinion on special points 
therein treated of, few we presume will deny that from the ap- 
pearance of the first edition of Professor Liebig's work on ' Or- 
ganic Chemistry in its Relations to Agriculture and Physiology * 
we may date a spirit of investigation into Agricultural Chemistry 
such as had not previously been manifested in this country. 
Indeed we conceive that in looking back to the words of his 
preface in 1840, wherein he says, '' I shall be happy if I succeed 
in attracting the attention of men of science to subjects which 
60 well merit to engage their talents and energies" — in this 
respect, at least, Professor Liebig must feel that his efforts have 
heea rewarded far beyond what his most sanguine expectation 
could at the time have led him to hope for. It could scarcely 
be expected, however, that with the progress of inquiry, such 
as is here invited, there should not result from time to time some, 
and perhaps material, modifications on questions which it is 
admitted the facts already at command were not competent 
satisfactorily to solve ; indeed, if it were not so, if no further 
facts were requisite, and the views as then put forth were all 
and in their manifold detail already fully substantiated, where 
the necessity for further investigation of the subject ? Surely 
it would be labour lost ! 

Professor Liebig has, indeed, himself contributed to the 
development of the subject in the several succeeding editions of 
his works ; and also in his ^ Letters on Chemistry ' and in other 
publications ; and he has, in a new and enlarged edition of the 
Beoond-mentioned work, namely, his ' Letters on Chemistry,' 
pablished only in May last, given the result of his latest re^ 
searches in agricultural and physiological chemistry. 

A X 



2 On Agricultural Clismistry. 

Among other labourers in this important field of investiga- 
tion of late years we may state that one of ourselves was occupied 
several years, prior to the appearance of the first edition of 
Professor Liebig's work, in investigating the action of different 
chemical combinations when applied as manures to the most 
important crops of the farm ; and that since the year 1843 we 
have been conjointly engaged in systematically investigating the 
subject of agricultural chemistry in a more extended sense than 
that alone implied in the question of the action of special sub- 
stances as manures. 

In the course of this inquiry the whole tenor of our results, 
and also of information derived from intelligent agricultural 
friends, upon every variety of land in Great Britain, has forced 
upon us opinions different from those of Professor Liebig on 
some important points ; and more especially in relation to his 
so-called *' Mineral Theory," which is embodied in the following 
sentence, to be found at page 211 of the third edition of his 
work on Agricultural Chemistry, where he says : *' The crops on 
a field diminish or increase in exact proportion to the diminu- 
tion or increase of the mineral substances conveyed to it in 
manure." 

It will be easily conceived, therefore, that it was with much 
interest that we turned to those pages of the new edition of 
Baron Liebig's * Letters,' which treat of the food of plants, 
in order to ascertain how far the facts of the last few years had 
tended to alter or modify his views on points wherein our own 
differed from those which he had hitherto published. 

It was in reference to our opinions on the views of Liebig, 
as given in the axiom already quoted, that Mr. Pusey, when 
giving, in the last number of this Journal, a review of the pro- 
gress of agriculture during the last eight years, called attention 
to what he regarded as conclusive evidence against those views 
in some of our results, which had appeared from time to time 
in former Numbers; and it is in reply to these remarks of 
Mr. Pusey that Professor Liebig has devoted a note of four or 
five closely printed pages in the * Letters ' just published to an 
attack upon our experiments and opinions, as set forth by Mr. 
Pusey in the article referred to. 

Of the vast importance, both in a scientific and practical 
point of view, of correct ideas on the subject here at issue, a 
judgment may be formed by the manner in which the Professor 
himself speaks of his '' Mineral Theory " in the new edition of his 
' Letters.' Thus, at page 483, he says of the agriculturists of 
England, that '' sooner or later they must see that in this so-called 
'mineral theory,' in its development and ultimate perfection, 
lies the whole future of agriculture." 



On Agricultural Chemistry, 8 

The importance of the subject on such high authority as 
that of Professor Liebig himself, as thus stated, will, we trust, 
be considered sufficient reason for bringing before the readers 
of this Journal a brief statement of the opinions to which our 
results have led us ; but as Professor Liebig has said, in regard 
to our experiments, that " they are entirely devoid of value, as 
the foundation for general conclusions ; " and, further, that ^' with 
a knowledge of our experience of the effects of fallow and of 
production on the large scale, it requires all the courage derived 
from the want of intimate acquaintance with the subject " to 
make the statements we have done, it seems incumbent on us 
to recall attention to the plan and object of the experiments 
themselves before entering upon the consideration of the results 
which they have provided. 

Looking upon the subject in a chemical point of view only, 
it would seem that an analysis of the soil upon which crops 
were to be experimentally grown, as well as a knowledge of the 
composition of the crop, should be the first points attained, with 
the view of deciding in what constituents the soil was deficient ; 
and at the commencement of our more systematic course of field 
experiments the importance of these points was carefully con- 
sidered. When we reflect, however, that an acre of soil six 
inches deep may be computed to weigh about 1,344,000 lbs. 
(though the roots of plants take a much wider range than this), 
and taking the one constituent of ammonia or nitrogen as an 
illustration, that in adding to this quantity of soil a quantity of 
ammonia-salt containing 100 lbs. of ammonia — which' would 
be an unusually heavy and very effective dressing — we should 
only increase the percentage of ammonia in the soil by 0*007, 
it is evident that our methods of analysis would be quite incom- 
petent to appreciate the difference between the soil before and 
after the application — that is to say, in its state of exhaustion, 
and of highly productive condition, so far as that constituent 
is concerned ; and from our knowledge of the effects of this sub- 
stance on wheat, we may confidently assert that the quantity of 
it supposed above would have given a produce at least double 
that of the unmanured land. The same kind of argument 
might, indeed, be adopted in reference to the more important of 
those constituents of a soil which are found in the ashes of the 
plants grown upon it, and we determined, therefore, to seek our 
results in another manner. Indeed, the imperfection of our 
knowledge of the productive quality of a soil, as derived from 
its percentage composition, has been amply proved by the results 
of analysis which have been published during the last ten years ; 
and in corroboration we need only refer to the opinions of 
Professor &f agnus on this subject, who, in his capacity of chemist 



4 On AgricitUural Chemishy. 

to the '* Landes-Oekonomie KoUeginm " of Prussia, has published 
the results of many analyses of soils. The truth is, that little is 
as yet known of what a soil either is or ought to be, in a chemical 
point of view ; but when we call to mind the investigations of 
Professor Mulder, in relation to the organic acids found in soils, 
and of Mr. Way and others, as to the chemical and physical 
properties of soils, in relation to the atmosphere, and to saline 
substances exposed to their action in solution, we may at least 
anticipate for chemistry that she will ere long throw important 
light on this interesting but intricate subject. 

In our field experiments, then, we have been satisfied with 
preserving specimens of the soils which were to be the subjects 
of them, and have sought to ascertain their deficiency, in regard 
to the production of difierent crops, by means which we conceive 
to be not only far more manageable, but in every way more con- 
clusive and satisfactory in their result. 

To illustrate — ^What is termed a rotation of crops is at least 
of such universality in the farming of Great Britain, that any 
investigation in relation to the agriculture of that country may 
safely be grounded on the supposition of its adoption. Let as, 
then, direct attention for a moment to some of the chief features 
of rotation. What is called a cou/rse of rotation is the period of 
years *which includes the circle of all the different crops grown 
in that rotation or alternation. The crops which thus succeed 
each other, and constitute a rotation, may be two, three, four, or 
more, varying with the nature of the soil and the judgment of 
the farmer ; but, whatever course be adopted, no individual crop 
— ^wheat, for example — is grown immediately succeeding one of 
the same description, but it is sown again only after some other 
crops have been grown, and at such a period of the rotation, 
indeed, as by experience it is known that the soil will, by direct 
manure or other means, have recovered its capability of pro- 
ducing a profitable quantity of the crop in question. 

On carefully considering these established and well-known 
facts of agriculture, it appeared to us that, by taking soils either 
at the end of the rotation, or at least at that period of it when 
in the ordinary course of farming farm-yaid-manure would be 
added before any further crop would be grown, we should then 
have the soils in what may be termed a norTnal^ or, perhaps 
better still, a practicaMy and a^griculturdUy e^hcuusted state. 

Now, if it is found, in the experience of the farmer, that land 
of any given quality with which he is well acquainted, will not 
when in this condition of practical exhatbstum yield the quantity 
he usually obtains from it of any particular crop, but that after 
applying farm-yard manure it will do so, it is evident that if 
we supply to different plots of this exhausted land the con- 



On Agricultural Chemistry. 6 

stitnents of &rm-yard manure, both individnally and com- 
bined, and if by the side of these plots we also grow the crop 
both withont manure of any kind and with farm-yard manure, 
we shall, in the comparative results obtained, have a far more 
satisfactory solution of the question as to what constituents 
were, in this ordinary course of agriculture, most in defect in 
respect to the production of the particular crop experimented 
upon, than any analysis of the soil could have given us. In 
other words, we should have before us very good ground for 
deciding to which of the constituents of the &rm-yard manure 
the increased produce was mainly due on the plot provided with 
it, in the case of the particular crop : not so, however, unless 
the soil had been so far exhausted by previous cropping as to be 
considered pradiically unfit for the growth of the crop without 
manure. We lay pEU*ticular stress on this point, because we 
believe that the vast discrepancy in the results of comparative 
trials with different manures, by different experimenters, arises 
more from irregularity in what may be called tkeflocUing capital 
of the soil than from irregularities in the original character of the 
soil itself, or from any other cause — unless we include the fre- 
quent faulty methods of application. 

It is, then, by this synthetic rather than by the analytic 
method that we have sought our results ; and in the carrying 
out of our object we have taken Wheat as the type of the cereal 
crops. Turnips as the type of the root aropsj and Beans as the 
representative of the Leguminous com crops, most frequently 
entering into rotation : and having selected for each of these a 
field which, agriculturally considered, was exhausted, we have 
grown the same desmption of crop upon the same land, year 
after year, with different chemical manures, and in each case 
with one plot or more continuously unmanured, and one sup- 
plied every year with a fair quantity of farm-yard manure. 

In this way 14 acres have been devoted to the continuous 
growth of Wheat since 184S, 8 acres to the continuous growth 
of Turnips from the same date, and 5 to 6 acres to that of 
L^^minous com crops since 1847. And of field experiments, 
besides these — which amount in each year to from 30 to 40 on 
Wheat, upwards of 90 on Turnips, and 20 to 80 on Beans — 
others have been made — viz. some on the growth of Clover, and 
some in relation to the chemical circumstances involved in an 
actual course of rotation, comprising Turnips, Barley, Clover, and 
Wheat, grown in the order in which they are here stated. 

It may be stated, too, that in addition to these experiments on 
wheat and the other crops usually grown upon the farm, as above 
referred to, we have for several years been much occupied also 
with the subject of the feeding of animals — viz. Bullocks, Sheep* 



6 On Agricultural Ghemistry, 

and Pigs — as well as in investigating the functional actions of 
the growing plant in relation to the soU and atmosphere ; and 
in connexion with each of these subjects much laboratory labour 
has constantly been in progress. 

The scope and object of oar investigation has been therefore 
to examine, in the field, the feeding^shed, and the laboratory, 
into t^e chemical circumstances connected with the agriculture 
of Great Britain in its four main features ; namely — 

First, the production of the Cereal grain crops ; 
Secondly, that of Root crops ; 

Thirdly, that of the Leguminous com and Fodder crops ; and 
Fourthly, and lastly, t£at of the consumption of food on the 
farm for its double produce of Meat and Manure. 

So much then for the rationale and general plan of the 
experiments themselves, and we now propose to call attention to 
some of the results which they have fforded us. 

Hitherto, only part of the results of the wheat experiments 
of the harvests of 1844, 1845, and 1846, and of these seasons 
only, have been published ; those on turnips, only for the sea- 
sons 1843, 1844, and 1845 ; those on the leguminous crops not 
at all as yet ; and those on feeding, only as far as sheep are con- 
cerned, and chiefly too in relation to the one point oidy of the 
increase of live weight obtained from a given quantity of food, or 
its constituents. Of the laboratory results, but few have been 
given in relation to any one of these branches up to the present 
time. The vast accumulation of results, indeed, will necessarily 
still further postpone the publication of them in any extended 
form ; and hence it seems the more desirable to take advantage 
of the present opportunity to attempt to bring together into one 
view some of the general indications which have been arrived at 
in relation to a few important points. 

With this view, it is to the field experiments on wheat that 
we shall chiefly confine our attention on this occasion; for 
wheat, which constitutes the principal food of our population, is 
with the farmer the most important crop in his rotation, all 
others being considered more or less subservient to it ; and it is, 
too, in reference to the production of this crop in agricultural 
quantity that the mineral theory of Baron Liebig is perhaps more 
prominently at fault than in that of any other. 

It is true that, in the case of vegetation in a native soil, un- 
aided by art, the mineral constituents of the plants being fur- 
nished from the soil, the atmosphere is found to be a suffidevU 
source of the nitrogen and carbon ; and it is the supposition 
that these circumstances of natural vegetation apply equally to 
the various crops when grown under euUivation that has led 



On Agricultural Chemistry, 7 

Baron Liebig to suggest that, if by artificial means we accumu- 
late within the soil itself a sufficiently liberal supply of those 
constitnents found in the ashes of the plant — essentially soil 
constituents — ^we shall by this means be able in all cases to in- 
crease thereby the assimilation of the vegetable or atmospheric 
constituents in a degree sufficient for agricultural purposes; 
But agriculture is itself an artificiai pi'ocess ; and it will be 
found that, as regards the production of wheat more especially, 
it is only by the accumulation within the soil itself of nitrogen, 
naiuraUy derived from the atmosphere, . rather than of the 
peculiarly soil-constituents, that our crops of it can be increased. 
Mineral substances will indeed materially develop the accumula- 
tion of vegetable or atmospheric constituents when applied to 
some of the crops of rotation ; and it is thus chiefly that these 
crops become subservient to the growth of the cereal grains ; but 
even in these cases it is not the constituents, as found coUeo- 
tively in the ashes of the plunts to be groum^ that are the most 
efficient in this respect ; nor can the demand which we find thus 
made for the production of crops in a^gricuUural quantity be 
accounted for by the mere idea of supplying the actual consti- 
tuents of the crop. It would seem, therefore, that we can only 
arrive at correct ideas in agriculture by a close examination of 
the actual circumstances of growth of each particular crop when 
grown under cultivation. We now turn to the consideration of 
our experiments upon this subject. 

It has been said that all the experimental fields were selected 
when they were in a state of agricultural exhaustion. The 
wheat-field, however, after having been manured in the usual 
way for turnips at the commencement of the previous rotation, 
had then grown barley, peas, wheat, and oats, without any 
further manuring; so that when taken for experiment in 1844, 
it was, as a grain-producer, considerably more exhausted than 
would ordinarily be the case. It was, therefore, in a most 
favourable condition for the purposes of our experiment. 

In the first experimental season, the field of 14 acres was 
divided into about 20 plots, and it was by the mineral theory 
that we were mainly guided in the selection of manures ; mineral 
manures were therefore employed in the majority of cases. 
Ammonia^ on the other hand, being then considered as of less 
importance, was used in a few instances only, and in these in 
very insignificant quantities. Bape-cake, as being a well- 
recognised manure, and calculated to supply — besides some 
minerals and nitrogen — a certain quantity of carhoTiaceous sub- 
stance in which both com and straw so much abound, was also 
added to one or two of the plots. 

The results of this first season (1844) having already been 



8 



On Agricultural Gheynistry. 



pretty fally detailed in this Journal, wet^an only give a summary 
of them in this place : — 

Tablb I.* 

Harvest 1844. Summaiy. (See first section of diagram I., 

opposite p. 14.) 



Deacriptton of the Mannret. 



ft 



ti 



tf 



•f 



Plot 3. Unmanured 

2. 14 toDs of farm-yard manure 

4. The ashes of 14 tons of farm-yard 

manure 

8. Mmimum produce of 9 plots with arti- 
ficial mioeral manures : — 

Superphosphate lime 350 lbs. 
Phosphate of potash 364 lbs. 
1 5. Maarimnm produce of 9 plots with arti- 
ficial mineral manures : — 

Superphosphate lime 350 lbs. 
Phosphate magnesia 168 lbs. 
Phosphate potash 150 lbs. 
Silicate potash 112 lbs. 

Mean of the 9 plots with artificial mineral 

manures 

Mean of 8 plots with mineral manures and 

65 lbs. each of sulphate ammonia 
Mean of 2 plots with mineral manures and 
150 lbs. and 300 lbs. of rape-cake respectively 
Plot 18. With complex mineral manure, 65 lbs. 
of sulphate of ammonia, and 150 lbs. of 
rape-cake 



} 



Total Ciorn 
per Acre, 
In BosheLi 
and PeeluL 



bush, pecks 

16 

22 

16 

16 1 



17 3J 



16 

21 
18 

22 



3| 



1 

8 



Total 

Ooni 

per Acre, 

inlba. 



Ibe. 
923 
1276 

888 
980 



1096 



1009 

1275 
1078 

1868 



Straw 

pttr Aora^ 

inlba. 



Iba. 
1120 
1476 

1104 
1160 



1240 

1165 

1425 
1201 

1768 



The indications of the table are seen to be most conclasive, 
as showing what was the character of the exhaustion which had 
been induced by the previous heavy cropping, and what, there- 
fore, should be the peculiar nature of the supply in a rational 
system of manuring. If the exhaustion had beea connected 
with a deficiency of mineral constituents, we might reasonably 
have expected that by some one at least of the nine mineral con- 

* It should be stated that the terms Superphosphate of Lime, Phosphate of 
Potash, Phosphate of Soda, and Phosphate of Magnesia, as used in this and the 
following Tables, and by which it Is convenient to designate the manures, are 
not to be understood as representing the chemical substances bearing those 
names. They were formed by acting upon burnt bone-dust by means of sul- 
phuric add in the first instance, and in the cases of the alkaline salts and the 
magnesian one by neutralising the compound thus obtained by means of cheap 
preparations of the respective bases. The silicate of t^otash was manufactured 
at a glass-house by fusing equal parts of pearlash and sand — a transparent 
glass, slightly deliquescent in the air, was the result. It was ground to powder 
under edge-stones. The Sulphate and the Muriate of Ammonia were such as 
are usually sold for the purposes of manure, and it may be estimated that one 
hundredweight of them respectively is equal to 100 lbs. of the pure crvstallised 
salt. The sulphurir aoid used was of the specific gravity of about 1*7. 



On Agricultural Chemistry, 9 

diticms — supplying in some cases an abundance of every mineral 
oonsdtaeat which the plant could require — this deficiency would 
have been made up ; but it was not so. 

Thaa, taking the column of bushels per acre as given in this 
summary, as our guide, it will be seen that whilst we have 
withont manure only 16 bushels of dressed com, we have by 
&rm-yard manure 22 bushels. The ashes of farm-yard manure 
give, however, no increase whatever over the unmanured plot. 
Again, out of the 9 plots supplied with artificial mineral manures, 
we have in no case an increase of 2 bushels by this means ; the 
produce of the average of the 9 being not quite 17 bushels. On 
the other hand, we see that the addition to some of these purely 
mineral manures of 65 lbs. of sulphate of ammonia — ^a very small 
dressing of that substance, and containing only about 14 lbs. of 
ammonia — ^has given us an average produce of 21 bushels. An 
insignificant addition of rape-cake too, to manures otherwise 
ineffective, has given us 18^ bushels ; and when, as in plot 
18, we have added to the inefficient mineral manures 65 lbs. of 
ammonia-salts, and a little rape-cake also, we have a produce 
greater than by the 14 tons of farm-yard manure. 

The quantities of rape-cake used were small, and the in- 
crease attributable to it also small, but it nevertheless was much 
what we should expect when compared with that from the 
ammonia-salts, if, as we believe is the case, the efiect of rape- 
cake on grairircrops is due to the nitrogen it contains. 

Indeed, the coincidence in the slight or non-effect through- 
out the mineral series on the one hand, and of the marked and 
nearly uniform result of the nitrogenous supply on the other, 
was most striking in the first year's experimental produce, and 
such as to lead us to give to nitrogenous manures in the second 
season even greater prominence than we had done to minerals in 
the previous one. This is in some respects, perhaps, to be re- 
gretlied, as had we kept a series of plots for some years con- 
tinuously under minerals alone, the evidence, though at present 
sufficiently conclusive, would have carried with it somewhat 
more of systemaiic proof. 

In Table II. (see following page) we have given a few results 
selected from those obtained at the harvest of 1845, the second 
of the experimental series. By the table it is seen that we have, 
at the harvest of 1845, a produce of rather more than 23 bushels 
withont manure of any kind, instead of only 16 as in 1844 ; and 
in like manner the farm-yard manure gives 32 bushels in 1845, 
and only 22 in 1844. We have shown in a former number of 
the Journal how clearly these differences can be traced to varia- 
tions in the climatic character of the season^ but this is not the 
point under consideration just now. 



10 



On Agricultural Chemistry, 



Harvest 1845. 



Table II. 

Selected Results. (See second section of diagram I. 
opposite p. 14.) 





Dressed Oorn 


Totol 
Cora 


Straw 


DMOription and QuantiUes of the MuinrM per Acre. 


per Aor^ 
in Buabds 


Acre, 




andPeoka, 


Acre, 
in lbs. 


in lbs. 




bush. 


peoka. 


lbs. 


lbs. 


Section 1. 










Plot S. No manure 


23 


Of 


1441 


2712 


„ 2. 14 tons of farm-yard manure 


32 


0^ 


1967 


3915 


Section 2. 










„ Ba. No manure ...... 


22 


2* 


1431 


2684 


„ 5h. Top-dressed with 262 lbs. of carbonate 










ammonia (dissolved), at 3 times, during 


26 


3J 


1732 


3599 


the spring 










Section 3. 










Q ( Sulphate of ammonia 168 lbs. > top-dressed t 
** * 1 Muriate of ammonia 168 lbs. ) at once ) 


38 


H 


2131 


4068 


2Q f Sulphate of ammonia 168 lbs. \ top-dressed > 
" \ Muriate of ammonia 168 lbs. i at 4 times i 


31 


8i 


1980 


4266 


vx. 


AOvv 


YArV^# 



We assume, then, 23 bushels or thereabouts to be the stan- 
dard produce of the soil and season, without manure, during this 
second experimental year ; and as part of plot 5 (previously 
manured with superphosphate of lime), and which is now, also, 
without manure, gives rather more than 22j^ bushels of dressed 
corn, tbe correctness of the result of plot 3, the permanently 
unmanured plot, is thereby fully confirmed. 

This plot No. 5, previously two-thirds of an acre, was, in 
this second year, divided into two equal portions ; one of these 
(" plot 5a ") being, as just said, unmanured, and the other (" plot 
bb ") having supplied to it in solution, by top-dressings during 
the spring, the medicinal carbonate of amvmonia^ at the rate of 
252 lbs. per acre : and it is seen that we have, by this pure 
but highly volatile ammonia-salt alone, the produce raised firom 
22^ bushels to very nearly 27 bushels ! 

In the next section of the table are given the results of 
plots 9 and 10, the former of which had in the previous year 
been manured by superphosphate of lime and a small quantity 
of sulphate of ammonia, and the latter by superphosphate of 
lime and silicate of potash. To each of these plots 1^ cwt. of 
sulphate and 1^ cwt. of muriate of ammonia were now supplied. 
Upon plot 9 the whole of the manure was top-dressed, a^ once^ 
early in the spring ; but on plot 10 the salts were put on at 
four successive periods. The produce obtained by these salts of 
ammonia alone is 33 bushels and three-eighths, when sown 



On Agricultural Chemistry, 1 1 

all at once, and nearly 82 bushels when sown at four different 
times — quantities which amount to about 10 bushels per acre 
more than was obtained without manure. In the case of No. 9, 
indeed, the produce exceeds by If bushel that given by farm- 
yard manure, and in that of No. 10 it is all but identiciEJ with 
it. And if we take the weights of total com, instead of the 
measure of the dressed com, to which latter we chiefly refer, 
merely as a standard more conventionally understood. No. 10, 
by ammonia only, has given both more com and more straw 
than the &rm-yard manure, with all its minerals and carbon- 
aceons substance. 

Let us see whether this almost specific effect of nitrogen, in 
restoring, for the reproduction of com, a corn-exhausted soil, is 
borne out by the results of succeeding years. 

In relation to the third experimental year (harvest 1846), we 
have already given in a tabular form in our former article most 
of the results ; but for want of time and space the attention 
of the reader was specially called to one or two of them only. 
We shall, therefore, on this occasion offer a few remarks on some 
of those not previously discussed ; and we should have omitted 
all reference to the results obtained with the wheat manure of 
Professor Liebig, to which we have already called attention, had 
not the professor, in the new edition of his 'Letters,' whilst 
fully admitting the failure of the manure — the composition of 
which, to use his o^d words when commenting upon it, '^ could 
be no secret, since every plant showed by its ashes the due pro- 
portion of the constituents essential to its growth " (page 482) 
— ^not expressed any doubt as to the principle involved in such 
a manure, but, on ike other hand, implied that the failure was 
due to a yet imperfect knowledge of the mechanical form and 
diemical qualities required to be given to the necessary con- 
stituents in order to fit them for tiieir reception and nutritive 
action on the plant, rather than to any fallacy in the theory 
which would recommend to practical agriculture the supply by 
artificial means of the constituents of the ashes of plants as 
manures. 

We do not mean to toy that Liebig's manure was not at 
&ult as to its mechanical form and chemical qualities, and from 
iheir failure the same might, perhaps, be said of all the mineral 
mixtures employed in our experiments. We must be careful, 
however, not to rely upon an argument of this kind without 
sufficient ground, for it must be observed that in this way every 
negative result of experiment whatever might be held as show- 
ing nothing, and indeed that every positive one was equally 
Utile to be trusted ; for it might be said that had we managed 
better, the one which is now negative might have been the 



12 



On Agricultural ClienUstry, 



most successful, and thus experiments of any kind would be at 
an end, and useless. 

But to return to the experiments. The following table gives 
our selection of the results of the third season, 1846: — 



Harvest 1846. 



Table III. 

Selected Results. (See third section of diagram I., 
opposite p. 14.) 



Deaoription and Quantities of the Manorea per Acre. 



Section 1. 



Plot 3. No manure .... 
2. 14 tons of farm-yard manure 



f« 



Section 2. 



•I 



>i 



«• 



10(. No manure .... 
10a. Sulphate of ammonia 224 lbs. 

Section 8. 

6a}. Ash of 3 loads of wheat straw . 
6a'. Ash of 3 loads of wheat straw, and 

top-dressed with 224 lbs. of sul 

phate of ammonia 

Section 4. 

6a. Liebig's wheat manure 448 lbs. 

6b. Liebig's wheat manure 448 lbs., with 

1 12 lbs. each of sulphate and 

muriate of ammonia 



Dressed Oom 

per Acre, 

in Bushels 

and Peokk 



bnsh. peeks. 

17 3} 

27 03 



17 
27 



19 
27 



n 





20 
39 



Of 



Total 

Com 

per Aoi^ 

in lbs. 



lbs. 

1207 
1826 



1216 
1850 



1306 
1827 



1400 
1967 



straw 
per Acre, 

in lbs. 



lbs. 

1613 
2464 



1455 
2244 



1641 
2309 



1676 
2571 



At this third experimental harvest we have on the con- 
tinuonsly unmannred plot, namely, No. 3, not quite 18 bnshels 
of dressed com, as the normal produce of the season ; and by its 
side we have on plot lOfc — comprising one-half of the plot 10 of 
the previous years, and so highly manured by ammonia-salts 
in 1846, but now unmanured — rather more than 17^ bushels. 
The near approach, again, to identity of result from the two un- 
manured plots, at once gives confidence in the accuracy of the 
experiments, and shows us how effectually the preceding crop 
had, in a practical point of view, reduced the plots, previously 
so differently circumstanced both as to manure and produce, 
to something like a uniform standard as regards their grain- 
producing qualities. We take this opportunity of particularly 
calling attention to these coincidences in the amount of produce 
in the two unmanured plots of the different years, because it has 
been objected against our experiments, as already published, 



On Agricultural Chemistry, 13 

that confirmation was wanting as to the natural yield of ami and 
season. 

Plot 2 has, as before, 14 tons of farm-yard manure, and the 
produce is 27^ bushels, or between 9 and 10 bushels more than 
without manure of any kind. 

On plot 10a, which in the previous year gave by ammonia- 
salts alone a produce equal to that of the farm-yard manure, we 
have again a similar result : for 2 cwts. of sulphate of ammonia 
has now given 1,850 lbs. of total com, instead of 1,826 lbs., 
which is the produce on plot 2. The straw of the latter is, how- 
ever, slightly heavier than that by the ammonia-salt. 

Again, plot 5a, which was in the previous season unmanuredj 
was now subdivided : on one half of it (namely, 5a^) we have the 
ashes of wheat-straw alone, by which there is an increase of 
rather more than 1 bushel per acre of dressed com ; on the other 
half (or 5a*) we have, besides the straw ashes, 2 cwts. of sulphate 
of ammonia put on as a top-dressing: 2 cwts. of sulphate of 
ammonia have, in this case, only increased the produce beyond 
that of 5a' by 72 bushels of com and 768 lbs. of straw, instead 
of by 9| bushels of com and 789 lbs. of straw, which was tho 
increase obtained by the same amount of ammonia-salt on 
10a, as compared with lOfc. It will be observed, however, that 
in the former case the ammonia-salts were top-dressed, but 
in the latter they were drilled at the time of sowing the seed ; 
and it will be remembered that in 1845 the result was better €U 
to com on plot 9, where the salts were sown earlier, than on plot 
10, where the top-dressing extended far into the spring. We 
have had several direct instances of this kind in our experience, 
and we would give it as a suggestion, in most cases applicable, 
that manures for wheat, and especially ammoniacal ones, should 
be applied before or at the time the seed is sown ; for, although 
the apparent luxuriance of the crop is greater, and the produce 
of straw really heavier, by spring rather than autumn sowings 
of Peruvian guano and other ammoniacal manures, yet we believe 
that that of the com will not be increased in an equivalent de- 
gree. Indeed, the success of the crop undoubtedly depends very 
materially on the progress of the underground growth during 
the winter months ; and this again, other things being equal, 
upon the quantity of available nitrogenous constituents within 
the soil, without a liberal provision of which the range of the 
fibrous feeders of the plant will not be such as to take up the 
minerals which the soil is competent to supply, and in such 
quantity as will be required during the after progress of the 
plant for its healthy and fiavourable growth. 

The next result to be noticed is that obtained on plot 6, now 
also divided into two equal portions designated respectively 6a 



14 



On Agricultural Chemistry. 



and 6b. Plot No. 6 had for the crop of 1844 superphosphate of 
lime and the phosphate of magnesia manure, and for that of 
1845 superphosphate of lime, rape-cake, and ammonia-salts. 
For this, the third experimental season, it was devoted to the 
trial of the wheat manure manufactured under the sanction of 
Professor Liebig, and patented in this country. 

Upon plot 6a, 4 cwts. per acre of the patent wheat-manure 
were used, which gave 20| bushels, or rather more than 2} 
bushels beyond the produce of the unmanured plot; but as 
the manure contained, besides the minerals peculiar to it, 
some nitrogenous compounds, giving off a very perceptible odour 
of ammonia, some, at least, of the increase would be due to that 
substance. On plot 66, however, the further addition of 1 cwt. 
each of sulphate and muriate of ammonia to this so-called 
^^ Mineral Manure " gives a produce of 29^ bushels. In other 
words, the addition of ammonia-salt to Liebig's mineral manure 
has increased the produce by very nearly 9 bushels per acre 
beyond that of the mineral manure alone, whilst the increase 
obtained over the unmanured plot, by 14 tons of farm-yard 
manure, was only 9^ bushels ! 

If, then, the *' mechanical form and chemical qualities " of 
the so-called ^^ Mineral Manure " were at fault, the sulphate of 
ammonia has, at least, compensated for the defect ; and even 
supposing a mineral manure, founded on a knowledge of the 
composition of the ashes of the plant, be still the great deside- 
ratum, the farmer may rest contented, meanwhile, that he lias in 
ammonia, supplied to him by Peruvian guano, by ammonia- 
salts, and by other sources, so good a substitute. 

In Table IV. are one or two of the results of the harvest of 
1847, which bear upon our question. 

Table rv. 

Harvest 1847. Seleoted Results. (See fourth section of diagram I., 

opposite p. 14.) 



Desoriptkm and QoantitiM of the llaniuras p«r Acre. 



Section 1. 
Plot 3. No manure .... 
2. 14 tons of fann-jard manure 



»t 



» 



»> 



i« 



Section 2. 

9a^ 1 ton of rice .... 

g , I Sulphate of ammonia 160 lbs. i 

(Muriate of ammonia ISOlbe. » 

g. ( Sulphate of ammonia 150 lbs. \ 

' t Muriate of ammonia 1 50 lbs. ^ 



DreeeedOom 

per Acre, 
InBodids 
andPecka. 




Tbtal 

Oom 

per Acre, 

inlbB. 



Straw 

per Aore, 

in lbs. 



Ibe. 

1902 
3628 



2606 
8062 

2868 



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On AgricuUural Chemistry^ 15 

The prodace of the continuously unmanured plot is now seen 
to be almost 17 bushels of dressed com, and that of the plot 
with farm-yard manure nearly 30 bushels. 

Plots 9a and 96, the former of which had in the previous 
season 4 cwts. of rape-cake, and the latter 4 cwts. of rape-cake 
and 2 cwts. of sulphate of ammonia, with no direct mineral 
manure in either case since the first season of 1844, were in 
this, the fourth season, set apart for the trial of some substance 
rich in cwrbon (but not so either in nitrogen or in mineral mat- 
ter), by the side of pure nitrogenous supply. Thus one half of 
9a (9a') was manured with ground rice^ at the rate of 1 ton to 
the acre. The other half of 9a (9a*) had 150 lbs. of sulphate 
and 150 lbs. of muriate of ammonia; as also had 96. The 
effect of the 1 ton of rice is to give 22| bushels of dressed com, 
or only 6 bushels more than the unmanured plot ; whilst the 
ammonia-salts of 9a^ and 96 gave respectively 26^ and 26 
bushels. That is to say, with a difference of only half a bushel 
in the two cases with ammonia-salts, an average is obtained 
of 9^ bushels more than on the unmanured plot. 

It surely is needless to attempt ftirther to justify, by the 
results of individual years, our assertion, that in practical agri- 
caltnre nitrogenous manures are peculiarly adapted to the growth 
of wheat. We shall therefore conclude this part of our subject 
by directing attention to the history of a few of the plots 
throughout the entire series of years up to the present time, as 
compared with that of the unmanured plot during the same 
period. 

The six next tables which follow (numbered V. to X. in» 
elusive) give the results of 6 of the plots thus compared with 
the unmanured one ; and in Table XI. we have the results of all 
those plots brought together in one view. 



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On Agrictdtural Chemistry. 23 

In Table V. we have compared together the produce of the 
nnmanured plot with that of Plot 10a, which, excepting in 
1844, when superphosphate of lime and silicate of potash were 
used (giving, however, less than half a bushel of increase), was 
manured in every succeeding season by ammonia-salts alone. 

It ifi a remarkable fact that from Plot 3 (the unmanured one) 
of this previously unusually corn-exhausted soil, we have car- 
ried from the land seven successive crops of wheat grain, and of 
straw, without any manure whatever ; and that under this 
treatment there are, at present, no signs of diminished fertility ; 
for lihe average of the seven seasons collectively is about 1 7 J 
bushels of dressed com, and about 16 cwts. of straw, or more 
than was obtained in the first experimental year. Indeed, there 
is little doubt that upon a soil of any given quality the produce 
will only vary with the character of the climate and the varia- 
tions of the seasons, which must materially affect the amount of 
ammonia available from natural sources ; and upon this again 
depends the assimilation of other constituents, which in the case 
of our experiments were proved to have existed in ample relative 
quantity within the reach of the plant. Thus, the results of 
Plot 10a, as seen in the 2nd column of the table, are alone 
sufficient to show that, whatever the deprivation by the pre- 
vious cropping, the soil still contained, relatively to the ammonia 
available from natural sources^ an EXCESS of the necessary mineral 
constituents. We shall presently show that this must be the 
condition of most if not all cultivated land, where grain and 
meai constitute — ^as they do, as the rule, in Great Britain — 
almost the exclusive exports from the farm ; the straw of the 
grain-^rops and the excrements of the animals fed upon the farm 
finding their way into the home manures, and eventually back 
again to the fields from whence they came. 

But we must not be understood to say that all soils will 
yield continuously 17J bushels of grain and 16 cwfcs. of straw 
per acre, without manure ; on the contrary, we know full well 
that they will not, and that what are termed light soils, but 
which, under high cultivation, give good crops of wheat, would 
give but a small proportion of this quantity. That the heavier 
ones do possess a native fertility beyond what might at first 
sight be supposed, there can be little doubt ; were it not so, 
we should find it difficult to explain how those who sell off 
their land almost all its produce without return, are enabled to 
live and pay their rent. But what we say is, that by the 
ordinary methods of practical agriculture, by which any soils 
are made to yield a fair produce of grain and meat only, for 
sale, their characteristic exhaustion, as grain producers, will be 
that of NITROGEN ; and that the mineral constituents will, under 



24 On Agricultural Chemistry. 

this coarse, relatively to nitrogen, be in excess. To this 
point, however, we shall recur farther on. 

Bat to retnm to the Table (V.) ; — a glance will show that in 
every season the produce was greatly increased by ammonia- 
salts only ; and in the last two years even, when the amount of 
ammonia supplied was increased, so also was there a greater in- 
crease of produce obtained than in previous years ; and this, not- 
withstanding there had been taken from the land in the previous 
rotation a heavy amount of minerals without return, and in the 
first five experimental crops the minerals, both of com and of 
straw, of crops as large as or larger than the average of the 
county under the ordinary system oi rotation and home manuring. 

The comparison afforded in Table VI. is very instructive. 
It gives the results of Plot 10ft, by the side of the unmanured 
plot. The manuring of this Plot 106 was, it will be remembered, 
in 1844, and in 1845, precisely the same as that for Plot 10a, 
last under consideration ; but in the succeeding years a different 
method of treatment was adopted. In this case, instead of 
giving year after year, as on 10a, ammonia-salts alone, these, 
on 106, have been alternated with no manure, with minerals 
alone, and with minerals combined with ammoniarsalts, in order 
to ascertain how far the characteristic result of each of the con- 
ditions, thus successively provided, would in each case be 
developed, independently of the immediately preceding supply. 

In the first year, the mineral manure gives less than half 
a bushel increase; — in the second, ammonia-salts give 8} 
bushels increase ; — in the third season, after a heavy dressing by 
ammonia, and a heavy produce, the cessation of manuring 
reduces the produce to a trifle below that of the unmanured 
plot; — ^in the fourth year, ammonia-salt alone increases the 
produce by one half; — in the fifth, a complex mineral manure, 
supplying nearly every mineral constituent of the crop in excess, 
and this combined with ammonia, gives an acreage produce even 
rather less than was obtained in the previous year without the 
minerals, and the proportion of increase over the unmanured 
plot is very little greater. In the sixth season we have, with a 
larger supply of nitrogen than usual, namely, with 200 lbs. of 
sulphate and 200 lbs. of muriate of ammonia per acre, an in- 
crease of 13 bashels, or more than two-thirds over the 
unmanured plot. And in the seventh and last completed 
experimental season, this very heavy dressing of nitrogen is 
succeeded by a very liberal supply of minerals, which minerals 
however raise the produce only two bushels above the yield of 
the unmanured plot. Nothing can be more striking and con- 
clusive than the evidence afforded by the fluctuations in the 
produce of this Plot 106, as showing that it would be much 



On Agricultural Chemistry. 25 

nearer the truth to say that the crop has risen and fallen in 
proportion to the diminution or increase of the ammonia supplied 
to it in manure, than of the mineral substances, as would be 
assumed according to the theory of Professor Liebig. It is 
seen, too, that it is only in the later seasons that the available 
minerals have appeared to be in defect, in relation to the nitro- 
genous supply. 

That the mineral constituents are indeed becoming deficient 
in several of the plots of our experimental fields, we have in our 
collective results, as well on turnips and beans as on wheat, 
abundant evidence ; and as the circumstances under which this 
point has actually been arrived at, 6re well understood, we are the 
better able to speak with confidence as to the non-exhaustion 
of them in other cases. Of this we shall on some future occa- 
sion speak much more in detail, when we are able to bring 
forward more of the experimental facts relating to it than we 
can do in a mere outline of this kind. But the plots to which 
we shall now refer will afibrd some illustration of it. 

We have seen, then, that on Plot 10a there has been in 
every year since the first experimental one a large amount of 
ammonia-salts, but without mineral supply ; and that by this 
means we have in every year obtained a considerable amount of 
produce beyond that without manure. In Plots 18a, 186, and 
17&, on the other hand, we have in every yea/r mineral supply ; 
and in 1846, and ever since, this has been the same for tiiese 
three plots, and always very liberal in nearly all the constituents 
required by the crop, — and in addition to this very liberal 
mineral provision, we have in each year, on one or more of these 
plots, exactly the same ammoniacal supply as in Plot 10a, which 
had no mineral manure, so that we are thus enabled to show at 
what point the mineral supplies of the native soil were, in 10a, 
deficient, in relation to the quantity of ammonia artificially 
applied to it. For the particulars of the manures of Plots 18a, 
186, and 176, we must refer the reader to Tables 7, 8, 9, respec- 
tively, but the comparisons of produce to which we wish now to 
call attention will be better seen in the summary table, No. 11. 
Thus, taking the cases of exactly similar ammoniacal supply, 
but in Plot 10a without mineral, and in the plot compared witl^ 
it, with minerals, we have in 1845, — 

Od Plot 10a, 31 1 bushels of dressed com and 4266 lbs. of straw, by 
168 lbs. each of sulphate and muriate of ammonia. 

On Plot 18, 33 bushels of dressed com and 3810 lbs. of straw, with only 
112 lbs. each of the ammonia-salts, but with mineral manure. 

In 1846, with equal ammoniacal supply in the two cases, we 
have, — 



\ 



26 On Agricultural Chemistry. 

On Plot 10^1 27 i bushels of dressed corn and 2244 lbs. of straw, without 
minerals. 

On Plot 176, 30^ bushels of dressed com and 2784 lbs. of straw, with 
minerals. 

In 1847, with ammoniacal supply only, we have, — 

On Plot 10a, 26} bushels of dressed com and 2891 lbs. of straw. 
On Plot 18a, 32^ bushels of dressed com and 3852 lbs. of straw, with 
minerals added. 

In 1848, we have, — 

On Plot 10a/ 19} bushels of dressed com and 2307 lbs. of straw. 
On Plot 18a, 26| do. do. and 2936 lbs. do. 

In 1849, we have, — 

On Plot 10a, 32^ bushels of dressed corn and 2861 lbs. of straw. 
On Plot 18a, 32 J do. do. and 3692 lbs. do. 

On Plot 176, 33} do. do. and 3868 lbs. do. 

with minerals added to the two latter plots. 

In 1850, again with ammonia-salts only, we have, — 

On Plot 10a, 27 bushels of dressed com and 3089 lbs. of straw. 

And the minerals and ammonia give — 

On Plot 18a, 29} bushels of dressed corn and 3927 lbs. of straw. 
On Plot 176, 29} do. do. and 4034 lbs. do. 

Thus it appears, then, that although Plot 10a, with ammonia- 
salts only, has given every year a considerable increase be- 
yond that of the unmanured plot, yet the ammonia-saIt« 
thus supplied were evidently much in excess over the minerals 
available within the soil ; for in every case when minerals have 
been also liberally supplied, we have in corn, straw, or both, a 
considerably larger increase still. In 1849, indeed, the exces- 
sively mineral-exhausted plot (10a) gives about the same 
quantity of corn as those which had always a liberal provision 
of mineral constituents. The straw, however, is deficient. 

The effect of mineral manures for the growth of wheat is 
then, in these cases, clearly shown : — but what are the circum- 
stances under which this result is obtained ? It is only when, 
after taking from the land the whole produce of a rotation 
without return, we provide ammoniansalts alone, in such quantity 
as to yield crops year after year as large as or larger than the 

* The produce of this plot being so small, we had been disposed to suspect 
that some mistake had arisen either during the harvest or at the time of 
turesbing. It was however observed that the crop in this season was par- 
ticularly irregular and sickly where there was a deficiency of minerals ; but 
as the produce of this plot (10a) was at the following harvest (184i)) con- 
siderably more than we should have anticipated, we are disposed to believe 
that the result as stated for 1848 is probably correct, and that the high rate 
of increase by ammonia-salts alone in 1849 was partly due to the n&n -ex- 
haustion by tho ( revious crop. 






On Agricultural Chemistry. 27 

average obtained in the county under the ordinary course of rota- 
tion and home manuring ; and the produce thus obtained by am- 
monia-salts only, was very nearly equal to that resulting from an 
annual supply of 14 tons of farm-yard manure. We by no 
means suppose, however, that if some cheap source of ammonia 
were discovered, we might with impunity continuously exhaust 
our soUs in the growth of com by its means ; but, on the con- 
trary, fully admit that under such a course our mineral supply 
i^ould soon become deficient. This is not the condition of 
Sritish agriculture, and it is not for such circumstances, there- 
fore, that we have at present to provide. 

But to recur to the siunmary table. We see that notwith- 
standing in the two cases there was an equal and very liberal 
supply of minerals in 18a and 186, we have with the cessation of 
ammoniacal supply in the latter, in 1846, a produce 10 bushels less 
than in the former, where the ammonia-salts were continued. 
The produce of 18i, indeed, with the minerals only, is S^ 
bushels of com and about 380 lbs. of straw more in 1846 than 
on the unmanured plot; but this exhaustion, by means of a 
liberal provision of minerals, seems to have been not without its 
effect upon the succeeding crap ; for although, in 1847, Plots 18a 
and 18^ are equal, both in mineral and ammoniacal manure, we 
have in the latter — which we have just seen gave 3 bushels 
increase under mineral only, in 1846 — 3 bushels less in 1847 
than 18a. The straw, however, of 18b is about 300 lbs. heavier 
than that of 18a. 

We may here observe that the production of straw, as well 
as that of grain, would seem to be intimately connected with 
the expenditure of nitrogen derived through the roots of the 
plant, and had we time to consider the question more fully on 
this occasion, we should not have dwelt so exclusively on the 
production of com alone as we have done. We may, however, 
remark, that the production of a heavy crop of straw in a wei 
season is probably, from the cause alluded to, a very dearly pur^ 
chased produce. 

We have already said that, excepting in the first two seasons, 
the mineral manures of 17b were exactly the same as those of 
18a and 186, and although we have seen that the miuerals of 
these plots have rendered the ammoniacal supply more effective 
than it was on 10a without the minerals, yet we observe that 
when, in 1847 and 1848, we give to 17i an additional quantity 
of ammonia-salt, the produce is increased beyond that of 18a 
and 18b. Thus we have in 1847, with an increased amount of 
ammonia-salt on 176, 3^ bushels more dressed com and about 
400 lbs. more straw than on 18a with its equal supply of 
minerals: and again, we have in 1848, on 176, two bushels more 



28 On Agricultural Chemistry. 

dressed com and nearly 400 lbs. more straw than on 18< 
clear, then, that the minerals supplied, which have been thi 
mach more than equivalent to those taken off in the ii 
produce, were only available so long as there was a libei 
vision of nitrogen in the soil ; and that when this ai 
supplied nitrogen was exhausted, the minerals remained 
and useless. We have, then, in the very cases where mi 
gave an increased produce, in the well-defined limit to] 
action which is indicated, further proof of the necessity 
artificial supply of nitrogen in the soU for the increased p] 
tion of corn, and the incapability of mineral supply to yiel 
increase, excepting when nitrogen is thus provided. 

Turning now to Table X., we find that the 98 tons of 
yard manure which have been supplied during the last 
years have only given an increase of 72^ bushels of dressedj 
and 3 tons 1 5| cwts. of straw over the unmanured plot, 
equivalent to only | of a bushel of com and | of a cwt. of 
for every ton of farm-yard manure supplied ! Parm-jj 
manure is, however, a very variable compound ; its composH 
being dependent upon the amount and quality of the food 
sumed by the animals which have produced it. Accon 
the mean of several direct experiments upon very rich 
manure, a ton of it, in round numbers, is composed of 14^ ci 
of water, and 5^ cwts. of dry substance, the latter of wl 
contains a large quantity of mineral matter and nitrogen eqi 
to about 20 lbs. of ammonia ; on the other hand, a ton of mani 
composed merely of straw wetted to the same degree, with 
course the same amount of dry substance, only gives niti 
equal to about 5 lbs. of ammonia, and probably much less 
half of the more important minerals of the rich box-manui 
The farm-yard manure carried out of our yards, as to nitrogei 
will generally have a composition intermediate between these 
two extremes ; and we may at any rate assume that that which! 
we employed would contain about 5 cwts. of dry substance, ol 
which the dry organic matter, rich in carbon, would be three or 
four times as great as, and the minerals also much in excess of, ] 
that required by the increase of com and straw which we have | 
seen to be obtained by their use. It is evident therefore that 
there must have been a great expenditure of non-nitrogenous | 
organic substance, and of mineral matter, without effopt ; and we 
conceive that the increase obtained was much moi^e intimately * 
connected with the amount of nitrogen contained in the manure 
supplied. This view, indeed, would appear to be beyond doubt 
when we consider that the application of ammonia-salts alone, 
during the last six years, as in Plot 10a, has given an average 
increase within two bushels of that which has been obtained by 
fhe use of farm-yard manure. 



-^ 



On Agricultural Chemistry. 29 

Neither Tnineral manures nor carbon, then, are indicated by 
our experiments as the special or direct manures for the growth 
of wheat. Not so, however, with the turnip, for the successful 
cultivation of which a liberal supply within the soil of carbona- 
ceous substance and phosphates is found to be important. We 
have here then a remarkable contrast — for if in practice the 
Wheat plant be supplied with a sufficient amount of nitrogen, 
it is not likely to be deficient in carbon or in mineral matter ; 
while the Turnip, on the other hand, will not be provided with 
the due quanti^ of carbon independently of a coincident and 
frequently sufficient supply of nitrogen. And it is in this con- 
version into useful food for stock by the Boot crop of the car- 
bonaceous matter of our straw which, after it has served as 
litter, would, beyond this, be a comparatively useless refuse of 
our grain crops, that phosphoric acid is foimdto be a very active 
agent ; whilst of the nitrogen stored up in the growth of the 
root crop, a much larger proportion than of the carbon remains 
in the excrements of the animals, and serves in its turn for the 
growth of the succeeding cereal grain : and hence is seen a 
mutual reliance between these two important crops of rotation. 
Bat to the influence of phosphoric acid upon the turnip crop we, 
shall recur again presently. 

But there is another point in connexion with the great 
demand made by the wheat plant upon nitrogen supplied to the 
sail, to which we wish to draw particular attention. 

Thus, among from two to three hundred experiments with 
ammoniacal manures, we have in no single instance recovered in 
the increase the amount of nitrogen provided in the manure ; 
and this fact is perfectly consistent witii the amounts of produce 
found, in the experience of the farmer, to be obtained by the 
use of Peruvian guano and other nitrogenous manures. Part of 
this result is doubtless due to the limited range of the roots of 
the plant in relation to the distribution of the manure in the 
soil ; but much of it is materially dependent on a definite 
expenditure, so to speak, of nitrogen, which is taken up by the 
roots of the plant and given off by its leaves to the atmosj^ere 
in the exercise of the functional actions of its growth. 

De Saussure, Daubeny, and Draper have found that nitro- 
gen was really thus given off during the growth of certain 
plants ; but in a practical point of view the question still arises 
whether this is uniform with all the different plants which enter 
into a rotation. 

In relation to this subject we have ourselves, during the last 
two years, undertaken a series of experiments, in the hope of 
sooner or later elucidating this truly interesting and important 
subject. We cannot here enter into a consideration of the results 



30 On Agricultural Chemistry. 

which have been thus obtained, but we may briefly indicate a 
probable conclusion to which the experiments would seem to 
lead, the results of a preliminary series of which have already 
been published in the Journal of the Horticultural Society, for 
January 1850. Thus we have found, that whilst for a given 
quantity of water passed through the plant during its growth 
the amount of non-nitrogenous substances fixed in it is, within 
somewhat narrow limits, identical ; that of the nitrogenous 
proximates fixed is, on the other hand, about tivice as great in 
the Leguminosae as in the Graminaceas. This fact, too, perfectly 
coincides with the results of our experiments in the field, with 
wheat and beans respectively, which show that under the same 
circumstances of growth, as to manure, &c., and in the same 
season, the acreage yield of nitrogen is twice or thrice as great 
in beans as in wheat. It cannot be supposed, however, that 
with the larger amount of nitrogen harvested in the leguminous 
crop the soil would be proportionally exhausted of it, for common 
practice teaches that, other things being equal, wheat, which is 
especially dependent on the supply of nitrogen in the soil, 
would give a larger produce after a bean than afber a wheat 
crop. 

Here then it would appear that there is evidence of a 
superior power in the leguminous as compared with the 
graminaceous plants, of obtaining their nitrogen from the 
atmosphere rather than from the soil ; or it may be supposed 
that the expenditure of it during the growth of the plant is 
greater in the one case than in the other. 

In support of the view that leguminous plants do possess a 
superior power of reliance upon the atmosphere for their nitrogen, 
and, indeed, that it is to this property that they materially owe 
their efficacy in rotation with grain, we may refer to the 
admirable investigations into the Chemistry of Agriculture of 
M. Boussingault. His experiments, however, have not received 
the attention which they merit from the agriculturists of this 
country ; probably on account of the small amounts of produce 
which he obtained. But it must be remembered that his in- 
vestigation had for its object to explain the practices of agricul- 
ture as he found them in his own locality, before attempting to 
deviate from its established rules. M. Boussingault states the 
rotation usually adopted at Bechelbronn, and throughout the 
greater part of Alsace, to be as follows ; — 

" Potatoes or beet- root," 

« Wheat," 

« Clover," 

•* Wheat ; " 
and that the average of wheat so obtained is, after potatoes. 



On Agricultural Chemistry. 81 

19^ bushels, after beet-root 17 bushels, and after clover 24 
boshels. Now we find by reference to his table that the first 
crop of wheat, grain and straw, removed 17 lbs. of phosphoric 
acid and 24 lbs. of potash and soda ; the following clover crop, 
18 lbs. of phosphoric acid and 77 lbs. of potash and soda ; and 
after this removal of alkalies and phosphates by the clover, a 
larger crop of wheat is obtained. Surely it would seem impos- 
sible to reconcile this result with a theory which supposes the 
produce of wheat to rise and fall with the quantity of minerals 
available within the soil. If, however, we admit that the first 
crop of wheat could not take up the mineral matters existing in 
the soil ft>r want of nitrogenous supply, and that the clover crop, 
not being so dependent upon supplied nitrogen, was able to 
take up the minerals required for its growth, and that it more- 
over left in the soil sufficient ammonia, or its equivalent of 
nitrogen in some form, to give the increased crop of wheat, we 
bave a much more consistent and probable solution of the results. 
There is little doubt that M. Boussingault could have increased 
his produce of wheat by means of ammonia-salts : whether he 
could have done so economically is another question, depending, 
of course, upon the relative prices of grain and ammonia. 

In onr paper upon the growth of wheat, published in the 
Jonmal of the Royal Agricultural Society in 1847, we have 
attempted an estimate of the probable amount of nitrogen re- 
quired to obtain a given amount of it in the increased produce. 
We there provisionally assumed that 5 lbs. of ammonia were 
required to produce an increase of one bushel of com and its 
equivalent of straw. We do not intend to enter fully into the 
qu^tion of the accuracy of this estimate on the present occasion, 
hut we may observe in paseiing, that among the plots the history 
of which we have given in the foregoing pages down to the last 
harvest, there is not one, even under the best conditions as to 
artificial mineral supply, where the ammonia, on the average of 
seasons, has given an increase equal to that supposed in our 
estimate. And even supposing that the farm-yard manure 
employed in onr experiments contained no more nitrogen than 
we have stated would have been provided in merely wetted straw, 
we have not obtained by its means as much as a bushel of com 
and its equivalent of straw for each 5 lbs. of ammonia thus 
^applied in the manure. It may be said, perhaps, that the cir- 
camstances of experiments wherein wheat has been grown for 
several years successively on the same land, are very artificial ; 
hut such is the result which they have yielded, and it is at 
any rate worthy of the serious attention of the reader. In some 
cases of onr experiments, however, which are in no degree less 

c 



32 On Agricultural Chemistry. 

artificial, a slightly better result has been obtained. But to this 
point we shall recur on some future occasion. 

Without further inquiring, then, into the correctness of our 
estimate, it would seem that a loss of this kind during the growth 
of the plant is a fact which is sufficiently substantiated, at once 
by the practical experience of the farmer, and by experiments of 
an independent kind relating to it. And, let it once be recog- 
nised, in agricultural science, that there is a definite expenditure 
or consumption of the nitrogenous bodies derived through the 
roots, connected with the fixation and elaboration of certain con- 
stituents of plants, and that this is greater or less according to 
the sources or the exact composition or state of elaboration of 
the products, and an important step will be gained towards a 
clearer conception of the principles involved in the alternation 
in a course of cropping, of plants of varying products and habits 
of growth. The fallacy, too, of the theory which would supply 
to plants a manure, founded on a knowledge of the percentage 
composition alone, whether of their ashes or of their organic 
substance, will at once be obvious. Nay, the converse of the 
axiom herein implied is more nearly true, at least in some 
important cases ; for, as we have elsewhere asserted, with regard 
to the Wheat and Bean plants for example, the former, that is, 
the Wheat, as compared with the latter, is characterised by a 
low percentage of nitrogen and a relatively high percentage of 
carbon ; but all experience and the tendency of all our results 
is to show, that the low nitrogenised Wheat crop requires for its 
luxuriant growth an abundant supply of m/ro^e?^ hj manure ^ and 
that with this it is practically independent of supplied carbon ; 
whilst the highly nitrogenous Leguminous plant is, other things 
being equal, by no means strikingly and characteristically 
benefited by nitrogenous manures. Weie it otherwise, where 
would be the subserviency of the leguminous plants grown in 
rotation with grain ? We had, indeed, at one time supposed 
that clover was greatly dependent on an artificial provision of 
nitrogen, but this view is not favoured by further investigation ; 
whilst with it, as well as with those leguminous plants valued in 
agriculture for their seeds, which are known practically to occupy 
a peculiar sphere when grown in alternation with the cereal 
grains, a mineral, and especially an alkaline manure, seems to be 
more prominently indicated. Indeed, it is to the fallmv crops 
generdly, or those which are grown in alternation with grain, 
that direct mineral manures are of essential service in enabling 
them to accumulate stores from the atmosphere ; and in this sense 
indeed special mineral manures may be said to be subservient to 
the increased growth of gi'ain ; and the effect of alkalies upon 
leguminous plants, perhaps, approaches more nearly to consist- 



Chi Agricultural Chemish*y, 33 

ency with the theory of Baron Liebig than any other fact 
which has come under our observation, for the alkalies, which 
we have found to have a very marked effect upon their increased 
growth, predominate largely in their ashes. 

A beautiful illustration of the dependence for luxuriant 
growth of one plant upon another of different habits, such as we 
have shown above, may be found in the case of the ** fairy rings," 
where the fttngus, by virtue of its extraordinary power of rapidly 
accumulating nito)gen from the atmosphere during its growth, 
taking up the minerals which the grasses, from their more 
limited power in this respect, could not appropriate, provides 
an abundance of the nitrogenous manure so effective in the 
growth of the grasses, which are observed to spring up with 
great luxuriance wherever the fungus has grown or fallen. 

But again, judging from the composition of the ash of the 
tarnip, which shows, both in the leaf and in the root, a pro- 
portion of alkalies to phosphoric acid of from four or five to one, 
we might be led to decide that the former, rather than the 
latter, were usually and specially the more appropriate manures 
for the turnip. Common practice has, however, definitely deter- 
mined in favour of phosphoric acid rather than of the alkalies, 
as the special manure to be provided for the turnip, from sources 
external to the farm itself. 

The striking effect of phosphoric acid upon the growth of the 
tnmip, indeed, is a fact so well known to every intelligent agri- 
culturist in Great Britain, that it would seem quite superfluous 
to attempt to illustrate it by any diirect experiments of our own. 
However, as Professor Liebig has again, in the recent edition of 
Ws * Letters,' expressed an opinion entirely inconsistent with 
such a result, we will refer to one or two of the results obtained 
in our experimental turnip-field, which bear upon the opinion 
te has reiterated as follows : — thus, speaking of the exhaustion 
of phosphate of lime and alkaline phosphates by the sale of flour, 
cattle, Ac., he says : — " It is certain that this incessant removal 
of the phosphates must tend to exhaust the land and diminish its 
capability of producing grain. The fields of Great Britain are 
^ a state of progressive exhaustion from this cause, as is proved 
V the rapid extension of the cultivation of turnips and mangold- 
^rzel, plants which contain the least amount of the phosphates, 

AKD THEREFORE REQUIRE THE SMALLEST QUAJJTITY FOR THEIR 

DEVELOPMENT ! " * Now we do not hesitate to say that, however 
small the quantity of phosphates contained in the turnip, the suc- 
<*8sfal cultivation of it is more dependent upon a large supply 
of phosphoric acid in the manure than that of any other crop. 

* See the third edition of the * Letters on Chemistry/ page 522. 



^ 



34 



On Agricultural Cliemistry, 



In the following table, then, is given the produce of roots * 
since 1843, of — 

First, the continuously unmanured plot ; 

Secondly, that with a large amount of superphosphate of 
lime alone each year ; and 

Thirdly, that with a very liberal supply of potash with 
some soda and magnesia also, in addition to super- 
phosphate of lime. 



It is seen then, that in the third season, viz. 1845, the 
produce of the unmanured plot is reduced to a few hundred- 
weights, and since that period the size of the roots has been 
such that they have not been considered worth weighing. On 
the other hand, on the plot with superphosphate of lime alone for 
eight successive years, we have an average produce of about 8^ 
tons of roots! varying, however, exceedingly, year by year, 
according to the season. We see, too, that by the addition to 
superphosphate of lime of a large quantity of the alkalies, much 
greater than could be taken off in the crop, the average produce 
is not so great by nearly half a ton as by the superphosphate of 
lime alone. It must be admitted that this extraoidinary effecfc 
of superphosphate of lime cannot be accounted for by the idea 
of merely supplying in it the actual constituents of the crop, 
but that it is due to some special agency in developing the 
assimilative processes of the plant. This opinion is favoured by 
the fact that in the case where the superphosphate of lime is at 
once neutralised by alkalies artificially supplied, the efficacy of 
the manure would seem to be thereby reduced. And from this 
again, we would gather that the effect of the phosphoric acid as 





Yean. 


Plot 

continuously T7n- 

manured. 


Plot 

with SaperphOB- 

phate of Lime alone 

erery Year. 


Plot 

with Superphoe- 

phate of lime and 

mixed AlkaliesL 






1843 


Tons. cwts. qra. lbs. 
4 3 3 2 


Tons. cwts. qrs. lbs. 
12 3 2 8 


Tons. cwts. qrs. lbs. 
11 17 2 




18 U 


2 4 10 


7 14 8 


6 13 2 






1845 


. . 13 2 24 


12 13 3 12 


12 12 2 8 






1846 




1 18 


3 10 1 20 






1847 




6 11 1 


5 16 






1848 




10 11 8 


9 14 2 






1849 




3 15 


3 13 2 8 


i 




1850 


 


11 9 


9 7 1 12 


• 




Totals. 




66 16 11 


62 5 1 20 






Means. 




8 4 2 4 


7 15 2 20 





* Norfolk Whites in 1843-4-6-6-7-8, and Swedes in 1849 and 1850. 



On Agricuitural Chemistry* 35 

Bncb, cannot be due merely to the liberation witbin the soil of 
its alkalies, or we should suppose that the artificial supply of 
these would at least have been attended with some increase of 
produce. But this is not the case, notwithstanding that by 
means of superphosphate of lime alone there has been taken 
from the land more of the alkalies in which the ash of the 
turnip so peculiarly abounds, than would have been lost from 
it in a century under the ordinary course of rotation and home 
manuring ! Collateral experiments also clearly prove the im- 
portance of a liberal supply of organic substance rich in carbon 
— ^which always contains a considerable quantity of nitrogen 
also — if we would in practical agriculture increase the yield 
much beyond the amount which can be obtained by mineral 
manures alone ; and these conditions being fulfilled, the direct 
supply of nitrogen, on the other hand, is by no means so gene- 
rally essential. And it is where we have provided a liberal 
supply of constituents for organic formations, in addition to the 
mineral manures, that we have found the use of alkalies not to 
be without effect. 

But it is at any rate certain that phosphoric acid, though it 
forms so small a proportion of the ash of the turnip, has a very 
striking efiect on its growth when applied as manure ; and it is 
equally certain that the extended cultivation of root crops in 
Great Britain cannot be due to the deficiency of this substance 
for the growth of com, and to the less dependence upon it of the 
root crops, as supposed by Baron Liebig. 

These curious and interesting facts in relation to the growth 
of turnips, as well as those which have been given in reference 
to wheat and to the leguminous crops, are sufficient to prove 
how impossible it is to form correct opinions on agricultural 
chemistry without the guidance of direct experiment in the 
field. And we are convinced that if Baron Liebig had watched 
the experiments which we have had in progress during the last 
eight years, he would long ago have arrived at conclusions in 
the main agreeing with those to which we have been irresistibly 
led : and we are disposed to believe that had he even seen the 
more detailed accounts of our results given in our own papers in 
this Journal, instead of the mere reference to them made by 
Mr. Pusey, he would rather have accepted them as a step in an 
inquiry to which his own researches and writings had given 
8Qch an impetus, than have designated them, as he has done, as 
entirely without value. 

So much, then, for the results of experiments in the field, 
and for the considerations in relation to the functional actions of 
plants, as bearing upon the character of the manure required for 
their growth in a course of practical agriculture. Let us now 






36 (hi Agricultural Ch&inistry. 

consider for a few moments what really are the main and cha- 
racteristic features of practical agriculture, as most generally 
followed in this country. 

Let us suppose that the rotation adopted is that of Turnips, 
Barley, Clover, Wheat ; that the turnips and clover are con- 
sumed upon the farm by stock, and that the meat thus produced, 
40 bushels of barley and 30 bushels of wheat, are all the 
exports from the farm, the manure from the consumed turnips 
and clover, and the sfcraw, both of barley and of wheat, being 
retained upon the farm. We have in this case, by the sale of 
grain, a loss of minerals to each acre of the farm of only 20 to 
24 pounds of potash and soda, and 26 to 30 pounds of phos- 
phoric acid, in the course of the rotation, or an average of 5 to 
6 lbs. of potash and soda, and 6^ to 7^ lbs. of phosphoric acid 
per acre per annum. In the sale of the animals there would of 
course be an additional loss of phosphoric acid, though, espe- 
cially if no breeding-stock were kept, this would be even much 
less considerable than in that of the grain ; and the amount of 
the alkalies thus sent oflF the farm would, according to direct 
experiments of our own upon calves, bullocks, lambs, sheep, and 
pigs, probably be only about one-fourth that of the phosphoric 
acid. It has, however, long been decided in practical agricul- 
ture that phosphoric acid may be advantageously provided in 
the purchase of bones or other phosphatic manures, though in 
practice these are not found applicable as a direct manure for 
the wheat crop ; and, as we have already said, even when em- 
ployed for the turnip, its efficacy is not to be accounted for 
merely as supplying a sufficiency of that substance to be stored 
up in the crop. 

Of the minerals then, to be supplied by external sources 
yet to be discovered or developed, the question lies with the 
alkalies ; and of these there will in the sales of com supposed 
above, be, under any circumstances, only 5 to 6 lbs. per acre per 
annum required to be provided from the stores of the native 
soil by annual decomposition, in order that the immediately 
available supply of them, which has thereby been drawn upon, 
should be undiminished* 

But we believe that few will maintain that the amounts of 
produce above supposed are, in practice, exported, unless under 
a system of purchased food for stock, or of such substances as 
rape-cake as manure for turnips ; and by neither of these means 
could the produce thus be raised, without bringing upon the 
farm more of the alkalies than eould possibly be exported, in the 
increased produce of corn and meat arising from their use. 
Under such a course, then, and this is what happens wherever 
land is well cultivated, the demand upon the native soil for 



On Agricultural Chemistry, 37 

alkalies, by the sale of com, will probably be less than has been 
assumed ; and it is even possible that in actual practice the 
available alkalies of the soil will, from the two causes of import 
and disintegration, accumulate rather than diminish. 

In justification of the supposition that cattle-food must be 
imported, if the sales of com and consequent export of alkalies 
are to be thus kept up, it must be remembered that the relative 
price of meat and corn, and that of manures to both, as fixed 
by the laws of supply and demand, would at present, at least, 
preclude the idea of the produce of the latter, that is corn, being 
maintained irrespectively of that of the former — that is to say, by 
imported manures alone, and to the exclusion of the consump- 
tion of food upon the farm by stock. And here we might 
suggest as a consideration well worth the attention of practical 
men, as a test of the "Mineral Theory," how it would be 
possible that the increased growth of wheat should be so 
limited and that its cost should be so great as in experience it 
is found to be, if the only manure required were the mineral 
constituents found in its ashes. And further,- we would ask 
how, on the idea, on the other hand, that the nitrogen supplied 
in our manures determines the produce of wheat, they could 
account for the relative prices of wheat and ammonia, unless on 
the supposition that the expenditure and loss of the latter 
during the growth of the plant, is a fact which fundamentally 
affects the production and cost of grain in practical agriculture.* 

But to return to our illustration. The animals kept upon the 
farm for labour too, must either consume part of the produce of 
the farm itself, in which case the sales of com must be reduced, 
and consequently the exhaustion of the alkalies also, or they must 
be provided for by purchased food ; in which case, while most or 
all of the minerals of such food will be retained upon the farm, 
much of its Nitrogen, and more still of its Carbon, will be lost by 
the vital processes. 

It will be understood that the precise circumstances assumed 
in the illustration which we have ^ven, will only be met with 
in certain cases, but whatever deviation from it may be found in 
ordinary practice in Great Britain, we believe that the line of 
argument here adopted is very generally applicable, and that it 
will also generally lead to a similar result. 

It is true that owing to proximity to large towns, or other 
local circumstances, in many cases hay and straw, and even 
root-crops, may be sent off the farm ; but in such cases local 



• One hondredweigbt of Peruvian gnano will supply as much pJiosphorio 
add as would be contained in about 18 bushels of wheat and its equivalent of 
straw— say 1,800 lbs. I And of nitrogen this quantity of guano will contain 
about as much as 11 bushels of wheat and 1,100 lbs. of straw 1 



38 On Agricultural Ohemistry, 

circumstances are generally found fully to compensate for this 
otherwise exhausting process, by the return of stable mannre, 
night-soil, and other natural town manures. Indeed, that the 
alkalies are not relatively to nitrogen exhausted by the sale of 
straw in the neighbourhood of London, for example, is evident 
from the extensive use and marked effects even of soot and other 
non-mineral manures on the land from which this straw is taken. 
But if it were not so, such instances need not come into oar 
calculations when speaking of agriculture generally. 

But further, Baron Liebig has said that a knowledge of our 
experience of fallow is sufficient to show the fallacy of our 
opinions ; but in this very process, and that even of liming also, 
when rightly considered, we believe we see that which should 
give confidence in the views we have maintained. It cannot be 
doubted that by the processes of fallowing and liming the dis- 
integration of the minerals of the soil, and the increase of the 
available supply therefore of their several constituents, must 
thereby be enhanced. But notwithstanding we have in the 
direct experiments of Wiegmann and Polstorff, of Rogers, and 
others, sufficient evidence of such disintegration under the action 
of air and water ; yet there is, in our opinion, equal reason for 
believing that the processes of fallowing and liming owe their 
efficacy, as much or more to the changes which take place within 
the soil in regard to the available supply of the nitrogen which 
plants require, as of their purely mineral constituents. Thus 
Professor Mulder has concluded that the organic acids of the 
soil which he has investigated, have the power of accumulating 
ammonia from the atmosphere. Now these compounds will only 
be retained within the soil where organic matter is subject to a 
very slow process of decomposition, and it is precisely in the 
heavier soilSy where the processes of fallowing and liming are 
found to be most beneficial, that organic matter will be shut up 
and subject to a very slow decomposing action, which these pro- 
cesses will materially assist. But more important still ; — ^the ex- 
periments of Mr. Way on the absorptive properties of soils have 
directly proved, what was before indeed supposed, that it is the 
heavier soils, those again therefore that are most influenced by 
fallowing and liming, that possess in the highest degree the 
power of absorption and retention of ammonia and other sub- 
stances, to the action of which they may be exposed. We do 
not, indeed, mean to say that the processes in question owe 
their value entirely to the influence of the actions to which we 
have alluded ; but we think it may reasonably be suggested that 
there is, at least, as much evidence in favour of this view, of the 
efficacy of fallowing more especially, as in the mineral theory of 
it ; and the more so when we remember that it is the wheat 



On AgricuUurdl Chemistry^ 39 

<nrop, for whicli nitrogen in the soil is found to be so important, 
that almost invariably succeeds the fallow. And the fact that 
mineral substances do at the same time accumulate, should itself 
^ve confidence in views which, on independent grounds, suppose 
that they are not so easily liable to be found in defect in relation 
to other necessary supplies. 

Be vie wing, then, the actual facts of practical agriculture, as 
generally followed in Great Britain, we have seen how small is 
the ntnaost annual loss of alkalies under the export of com and 
meat alone, and that the demand thus made upon the stores of 
the native soil will generally be truly insignificant. Phosphoric 
acid, on the other hand, is sent off the farm in much larger 
quantities than the alkalies ; but under good cultivation it is 
already in actual practice frequently more than restored by the 
import of cattle food, or direct manures, such as bones, guano, &c. 
Baron Liebig, indeed, himself asserts that farm-yard manure is 
the universal food of plants ; and we should never lose sight of 
the fact, that the very practice of agriculture in this country 
necessitates the production of this manure, by means of which it 
is that so large a proportion of the mineral elements of the crops 
raised upon the land are in due time restored to it ; all our cal- 
culations, therefore, should be made on a full consideration of 
what is involved in its use. This is, however, not generally 
sufficiently borne in mind by chemists unconnected with prac- 
tical agriculture ; and to this cause may, in great part, be attri- 
buted the reiterated recommendations to imitate in artificial 
manures the composition of the ashes of the plants to be grown. 
But further than this, taking into careful consideration the 
tendency of all experience in practical agriculture, as well as 
the collective results of a most laborious experimental investi- 
gation of the subject, both in the field and in the laboratory, it 
is our deliberate opinion that the analysis of that portion of a 
crop which is sent off the farm, whether of its organic substance 
or of its ashes, is no direct guide whatever as to the nature of 
the manure required to be provided for its increased growth in 
the ordinary course of agriculture, from sources extraneous to tlie 
home manures of the farm ; that is to say, by artificial means. 

In conclusion, then : if the theory of Baron Liebig simply 
implies that the growing plant must have within its reach a 
sufficiency of the mineral constituents of which it is to be built 
up, we fully and entirely assent to so evident a truism ; but, if, 
on the other hand, he would have it understood that it is of the 
mineral constituents, as would be collectively found in the ashes 
of the exported produce, that our soils are deficient relatively to 
other constituents, and that, in the present condition of agri- 
culture in Great Britain^ " we cannot increase the fertility of 



n 



40 On Agricultural Chemistry. 

our fields by a supply of nitrogenized products, or by salts of 
ammonia alone, but rather that their produce increases or 
diminishes, in a direct ratio, with the supply of mineral elements 
capable of assimilation," we do not hesitate to say that every 
fact with which we are acquainted, in relation to this point, is 
unfavourable to such a view. We have before stated, however, 
that if a cheap source of ammonia were at command, the avail* 
able mineral constituents might in their turn become exhausted 
by its excessive use. 

Baron Liebig states indeed (see *' Letters on Chemistry," p. 5 1 9), 
that his views are '^ in no respect inconsistent with the good 
effects of an artificial supply of ammonia ; " — that " a supply of 
it is always beneficial, and for certain objects indispensable ; 
and that it '^ accelerates * the development of cultivated plants ; 
— ideas which, we would submit, are not consistent with the 
supposition of a relative deficiency of minerals in our soils, and 
which, if he carried out to their consequences, would materially 
lessen the difference between his opinions and our own. But as 
he says in the same page, that " if the mineral elements, phos* 
phates, &c., be duly supplied, the plant will obtain a sufficient 
supply of ammonia from the atmosphere," the practical utility of 
its application by artificial means would seem at the same time 
to be put out of the question. 

He further states (p. 519) that " the supply of ammonia is 
for many of our cultivated plants unnecessary and superfluons." 
This seems fully to imply a distinction among the plants grown 
in our rotations, as regards their demand for nitrogen accumu** 
lated in the soil in the course of cultivation, and, in fact, that 
for some plants such a supply i^ necessary. Here is a point 
which we have claimed to be intimately connected with the 
utility of a rotation of crops. But when he says in the same 
chapter (p. 514), "Surely the cerealia and leguminous plants 
which we cultivate must derive their carbon and nitrogen frons 
the same source whence the gramineous and leguminous plants 
of the meadows obtain them," he would seem to bring all again 
within one category. 

In another chapter (p. 524) he says that if " a rich and cheap 
source of phosphate of lime and the alkaline phosphates were 
open to England, there can be no question that the importation 
of foreign com might be altogether dispensed with after a short 

* At the recent meeting of the British Association at Ipswich, where the 
substance of this paper was given, Dr. Daabeny brought forward Baron 
Lie big's admission of the *' acceleration *' of the growth of plants by ammonia, 
as showing his recognition of the importance of its artificial supply; an^ 
hence, t.o avoid misconception, it seemed desirable, by means of .further quota* 
ions, to show what really are the views of Professor Liebig on this point. 



On Agricultural Chemistry. 41 

time." But it is at any rate certain that for wheat, of all our 
crops, no supply of minerals, phosphates, &c., to the fields of 
Great Britain generally, will enable it to " obtain a sufficient 
supply of ammonia from the atmosphere ; " and, indeed, that 
any increased produce of it, such as British agriculture (itself so 
artificial) demands, cannot be obtained independently of an 
artificial accumulation of nitrogen within the soil. 

Of those crops of rotation, on the other hand, where the effect 
of mineral manures is characteristically to increase the assimila- 
tion of nitrogen from atmospheric sources, and by virtue of which 
property they indeed become subservient to the increased growth 
of grain, the apparent demand for these substances is not only 
generally not such in kind as would be indicated by an analysis 
of their ashes, but is frequently much greater as to quantity th&n 
can be accounted for by any idea of merely supplying what is to 
become an actual constituent of the crop. If, then, we would 
attain by the aid of science a rational system of agriculture, the 
actual facts of the art itself, as well as the indications of direct 
experiments in the field, and a study of the functional actions 
of plants and animals, must receive a due share of our atten- 
tion. In fact, chemistry alone will do nothing for practical 
agriculture. 



Note. — ^This important paper so completely establishes what 
I wrote in our last Number on the entire failure of the Mineral 
Theoiy as a guide to the use of manures in practical farming, 
that I need only express my regret for the annoyance which its 
author has publicly expressed, as I am told, at those remarks. 
In cautioning the English farmer against what seemed to me a 
dangerous error, I certainly endeavoured to do justice to the real 
discoveries of Baron Liebig. Since the experiments, however, 
of Mr. Lawes and Dr. Gilbert have, as I hear, been disputed, I 
am bound to say that my confidence in the scrupulous accuracy 
of those gentlemen has been only strengthened by a subsequent 
visit to Rothamsted, in company with that eminent philosopher 
Mens. Dumas. The extent of the experimental ground — the 
expenditure at which it has been kept up — the perseverance 
with which, year after year, it has been maintained, are such 
as might rather be expected from a public institution than 
a private landowner, and render Rothamsted, at present, the 
principal source of trustworthy scientific information on Agri- 
cultural Chemistry. 

Ph. Pusey. 



raiXTED BT 
BPOTTIBWOOOE AND CO., KBT7-8111KIT SQUARI 

WSDOK 



ON THE 



AMOUNTS OF, AND METHODS OF ESTIMATING, 



AMMONIA AND NITRIC ACID 



IN 



RAIN-WATER. 



BT 



J. B. LAWES, F.R.S., F.C.S. ; and Dr. J. H. GILBERT, F.C.S. 



[From ihe Report of the British Aflsociation for the Advanoement of Science for 1 854.] 



LONDON : 

PBINTED BY TAYLOR AND FRANCIS, 

Red Lion Court, Fleet Street. 

1856. 



RE-PRINTED BY DUNN AND CHIDGEY, 
155 Sc 167, KING8LAVD Road, N.E. 

1889. 



ON THE 



AMOUNTS OF, AND METHODS OP ESTIMATING, 



AMMONIA AND NITRIC ACID IN EAIN- WATER, 



The character and amount of the extraneous matters in rain-water are 
qa^ions of interest in so many points of view, that little apology need he 
made for recording, under the auspices of the British Association, any addi- 
ikoal information on that suhject. Of all such extraneous matters, the 
ammonia and nitric acid are of importance in the most numerous aspects. 
Thus, their existence in the atmosphere, from which they are washed by the 
rain, is primarily dependent, largely at least, on the emanations from the 
surface of the earth, resulting more or less directly from the decomposition 
or oombnstion of animal and vegetable substances, and the transformation of 
the animal substance by the vital process. Their amounts therefore must be 
gieat^ or less in the lower strata of the atmosphere, according to the local 
prevalence of animal life and other causes, whilst the relative amounts of 
the two,e8peciaUy in the higher strata of the atmosphere, will be dependent 
on its meteoric or electrical condition. Again, whatever may be their source 
or amount, or their proportion to each other in the atmosphere itself, the 
amounts of them which are carried down in rain and the minor aqueous 
depositioDS from the atmosphere in any given locality, over any fixed period 
of time, or according to other circumstaoces, must be of interest at once iu 
a sanitary, in a meteorological, and in an agricultural point of view. 

It is to Cavendish that we are indebted for the observation, that ammonia 
and nitric acid are formed when humid air is submitted to voltaic action. 
About the commencement of the present century, De Saussure detected 
ammonia in the atmosphere. A few years later, Ghevreul observed its pre- 
aeoce in the Seine ; and in 1825, Brandos detected it in rain-water. Since 
that time much more minute attention has been paid to this subject, and 
ako to the presence of nitric acid in rain and other waters. Liebig, and 
Bouflsingault, have particularly called attention to the influence which the 
unmonia carried down from the atmosphere must have upon the growth of 
plants ; and the former of these philosophers pointed out the occurrence of 
nitric acid also, in a considerable number of rain-waters which he examined, 
especially in those of thunder-storms ; though to the amount of nitrogen 
80 brought down he attached little importance. Dr. H. Bence Jones has 
ako found nitric acid in the rain which fell in various parts of England 
and in the south of Ireland. 

Bat it is to the more I'ecent labours of Boussingault that we are indebted 
for oar most elaborate quantitative estimations of the ammonia in rain and 
other waters ; and M.Barral has made a series of quantitative determinations 
of the mtric add as well as the ammonia, contained in the rain which fell at 
Paris during several consecutive months in 1851. Our own object in 
entering upon the same field of inquiry, was chiefly with a view to the 



agricultural bearing of the subject. But the conduct of an investigation 
involving at once the treatment of large bulks of material, and the determi- 
nations in them of infinitesimally small amounts of the substances sought 
for, is attended with many practical difficulties: and the scope and object of 
the present paper is rather to discuss the methods of analysis, than to rely 
with confidence on the conclusions to which we might be led by the direct 
appUcation of the numerical results yet obtained, to the solution of the 
several important scientific and practical questions upon which they bear. 

In the Tables which follow are given the results obtained in the estimation 
of ammonia in rain-water by several different methods. In the first instance, 
very large amounts (from 100 to 200 lbs. or more) of rain-water, to which a 
httie caustic potash was previously added, were distilled, and the distillation 
of the product repeated, collecting in each case about one-half the amount 
put into the retort, until the whole was reduced to a conv^enient bulk for 
further treatment. This was then evaporated in an open vessel, with a known 
amount of sulphuric acid to a givm twlum$. Measured portions of this acid 
product were then neutralized by a standard alkaline solution, in the usual 
manner of liquid analysis. This process we designate as " Method 1.*' 

The system of graduation adopted throughout the experiments was that 
of septems, this bemg generally employed in water analyses in Great Britain. 
As cubic centimetres and litres are generally adopted abroad, it may facilitate 
the conception of those accustomed to the latter measures, to state, that the 
septem is equal to 7 grains of water at 60^ ; that 1000 septems are equal to a 
decigallon, or 1 lb. ; and 10,000 septems consequently are equal to 1 imperial 
gallon. A cubic centimetre, on the other hand, is equal to 1 gramme, or 
rather less than 15^ grains ; ancl 1000 cubic centimetres, or grammes, are 
equal to 1 litre. Consequently, for the purposes of a general conception 
merely, a cubic centimetre may be considered as eoual to 2^th septems, and 
a litre to 2ith decigallons, or lbs. avoirdupois. We shall, however, always 
give the amount of ammonia found in one million parts of rain-water, which 
is precisely equivalent to the scale of milligrammes of ammonia per litre 
(1,000,000 milligrammes) of water, as adopted by MM. Barral, Bonssin- 
gault, and others. The sulphuric acid used in the determinations made by 
Method 1 , was at " 10^ " strength, 1000 septems of which contain 50-1 grains 
(one tenth the combining number) of the dry acid ; 1 septem, therefore, of 
this liquid acid contains 0*0501 grain of the dry acid, and is equivalent to 
the neutralization of 0*02145 grain of ammonia, which is=xi7,|enyth of Ber- 
zelius's number for ammonia. The acid was prepared by dissolving 66'78 
grains (one tenth the combining number) of pure carbonate of soda in 1000 
septems, or a decigallon, of distilled water at 60**, and then making a pre- 
viously dilute acid to exactly the same strength, volume for volume, by the 
usual alkalimetrical method ; and, from this acid at lO'^, the standard caustic 
alkali solutions were made of a hke strength, in a similar manner. The above 
acid is exactly one-seventh the strength of Peligot's acid. 

In Table f. which follows, are given the results of the determinations of 
the ammonia by this " Method 1," in the mixed sample for each month, of 
the rain w^hich fell in March, April, May, June, July, and August, of 1858. 
The quantities operated upon were one-half or one-fourth of the total 
amounts collected m each month, in a rain-gauge of exactly jiAnrth of an 
acre area (48'56 square feet). 



Table I. 

Method 1. — The Rain twice distilled to fths with a little caustic alkali, and 
the second distillate evaporated with sulphuric acid to the measure of 
1000 septems. (Year 1853.) 



Monihfl. 


Ibfi. of rain 
difitmed. 


Septems of 

iialphnric 

acid at 10<» 

added to 

second 
distillate. 


Septems of 
allcall at lO^' 
to nentralise 
lOO septems 
of concen- 
trated acid 
product. 


Diflterence 
— septemft 

ammonia at 
10« in 100 

septems aoid 
prodoct. 


OrainA of 

ammonia in 

rain-water 

taken. 


Ammonia 
per million 

of 
rain-water. 


Much ... 
April 

Miy 

June 

July 

Aogost... 


267-2 
169-6 
95-2 
176-2 
213-0 
167-9 


800 j 
400 1 
300 1 
700 1 
500 1 
400 


17-6 
17-5 

36-5 
35-5 

25-5 
25 5 

62-0 
62-0 

4S'5 
43*5 

35-5 


12-5 ) 
12-5 ] 

4-5 ) 
4-5 ] 

4-5 \ 
4-5 ] 

8-0 j 
80 ] 

6-6 1 
6-5 ] 

4-5 


2-681 
0-965 
0-965 
1716 
1-394 
0-965 


1-483 

0-812 
1448 
1-399 
0-935 
0-821 



It is seen that the smallest quantity of water submitted to distillation in 
tins series of experiments was about 95 lbs., and that the largest was about 
U7 Ihs. To the second distillate of fths of the amount put into a retort of 
glass, with a little caustic alkali, the quantities of sulphuric acid at 10^ given 
in ooimnn 8 were added, and the whole was then evaporated to the measure 
of 1000 septems at 60**. One-tenth of this, or 100 septems, after being 
cokynred by a given measure of infusion of htmua carefully freed from excess 
of alkali, was then tested with a caustic alkaU solution, also at 10^. It was 
inTariaUy found, that, with liquids of this degree of concentration, the deter- 
BUDStion could be made to a smgle drop of the test alkali. This would give 
a maximum range of error of about yV^h, or 2 per cent, of the whole am- 
inoma contained in the water, dependent on the manipulation of the test 
lienors. It was still a question whether there might not be some source of 
cnor, either in assuming with M. Boussingault that the whole of the ammonia 
vonld be obtained in a f ths distillate, or in supposing that there would be no 
Ion either of ammonia or of acid, in the evaporation of the acidulated di- 
stillate in open vessels. By the comparison which wiH presently be made, 
^wever, between t^e above determinations by Method 1, and others in 
^mens of the same waters by Method 2, which in fact is that adopted by 
K. Boussingault, it will be seen that there was probably no error due to 
^er of the causes just suggested. In fact we conceive that the method of 
^ distillation, with sube^uent acidulation and ooncentration of the di- 
s^llate to a given measure of fluid, and the use of comparatively strong test 
%iids, is capable of giving very good results ; but it was necessarily aban- 
4>ned from the great practical inconvenience, and frequent breakage, in 
oondncting distillations in glass on so large a 8(^e. 

In the next Table (II.) are riven the actual results obtained by Method 2 ; 
^h is substantially that of M. Boussingault. M. Boussingault's process 
^»»i8t8 in submitting to a single distillation, generally not more than 1 litare 



(about 86|^ ounces) of water, and collecting and testing by the alkalimetrical 
method, two or more successive fifths or tenths of the product. For this 
purpose M. Boussingault uses a test acid little more than |th the strength of 
our acid at 10°, and only ^^V^h the strength of the test acid of M. Peligot. 
His test alkaline solution^ again, is not quite ^rd the strength, volume for 
volume, of his test acid. In practice he nnds mat the limit of error in the 
use of this dilute alkaUne solution is about 0*2 cub. cent, measures of it, equal 
to about 0*033 milligramme, equal to 0*0005 grain of ammonia. This, equal to 
about ^injifth of a grain only, is certainly a suprisingly small actual amount 
of ammonia to determine by analysis ; but when it is considered, that in the 
quantity of water operated upon by M. Boussingault, there is seldom 1 mil- 
]igramme=0*0154 grain of ammonia, it is obvious that an error of only 
0*033 milligramme or 0*005 grain, however small in actual amount, is still 
considerable in the relation to the whole to be estimated, amounting in the case 
supposed to about ^V^h or 3^rd per cent. But when we further consider, that 
the total amount of ammonia in a litre of water is frequently considerably less 
than a milligramme, and also that this total amount, whatever it may be, is 
divided for testing into two or more seperate portions of the distillate, it is 
obvious that the minimum range of error, especially in the testing of the 
weaker portions, must be very considerable indeed in proportion to its whole 
amount. We have, however, had the privilege of witnessing the conduct of 
the process in the hands both of M. Boussingault and of his able assistant 
M. Houzeau, and certainly with suprising uniformity of result. 

In Table II. are given the actual results of experiments in the Rothamsted 
Laboratory, in which 60 ounces, instead of only 1 litre, were generally 
submitted to distillation ; and although the greatest care was taken, it must 
be admitted that in these first results of unpractised hands, neither was the 
relation of the ammonia in the successive portions of the distillate so uniform 
as in the experiments of M. Boussingault, nor were the total amounts of 
ammonia found in duplicate specimens of water so coincident as could he 
wished. But it must be clearly understood, that attention is called to this 

eint not in the least with the view of depreciating the admirable labours of 
. Boussingault, which we are satisfied have been conducted with the utmost 
accuracy of which the process is capable, but it seems desirable to point out 
how serious may be the proportional error in less constantly practised or less 
careful hands. 

It should be mentioned, that in our conduct of this Method 2, in all cases 
excepting for the month of April, a test acid of 1° strength only was em- 
ployed ; that is to say ^V^h the strength of that used previously, and it was 
moreover only about |ths the strength of Boussingault's acid. The test 
alkali, on the other hand, was, for the rain of the first four months, at 1^, 
and afterwards at only ^^ strength, which latter is very nearly identically 
the same as that used by Boussingault. We sought to measure too, to a ^th 
of a septem of the stronger, and \ a septem of the weaker alkaline test- 
liquor, which respectively represent^ 0*034 milligramme, or 0*00054 grain 
of ammonia, almost identically the same degree of accuracy as that attained 
by M. Boussingault in measuring to 0*2 cub. cent, of his alkah=0*0S8 milli- 
gramme of ammonia. The fractional distillates were collected in small 
flasks marked according to the quantity to be coUecte i, each of which, 
when filled, was corked up until the series was ready for testing. An 
equal measure of pure distilled water was then put into a test-glass side by 
side with the distillates, and to it was added the same measure of litmus 
and acid as to the rain products. This being neutralized with its exact 
'univalent of the test-alkali, furnished a guide as to the tint to be aimed 



at in the other testings, which were then performed as rapidly as possible, 
to prevent the absorption of carbonic acid from the atmosphere. It >vas 
found by nmnerons trials, that this adoption of a standard — and com- 
pared with the method of M. Boossingault somewhat more permanent point 
of coloration — gave ns greater uniformity of resalt in duplicate experiments 
with liquids of known strength, than that of taking the point of first perfect 
diffosion of blue colour throughout the liquid, as adopt^ by Boussingault ; 
and the test-liquors were therefore arranged accoraingly. It should be 
added, that the rapid diffusion of the alkali through the Uquid was favoured 
bj increasing its specific gravity by the addition of neutral sulphate of 
potash as employed by M. Boussingault for that purpose. 

Table II. 

M$ihod 2. — By the single distillation of small quantities of water (with 
alkaU), and testing successive portions of the distillate according to 
Boussingault. 





s 




Septems of Ammonia at l^ in portione of distillate. 


 • 


Tflsr 18U. 


§ 
1 

1 
2 


OnnoeR 
of 
















Immonia 

per 
million 


Y »■* 


snd 
tenth, 
or let 
fifth. 


8rd 
tenth. 


4th 

tenth, 

or Snd 

fifth. 


5th 
tenth. 


6th 

tenth, 

orSrd 

fifth 




Monthii. 


water. 


l8t 

tenth. 


ToUl. 


rain- 
water. 


April ... 


so 

30 


... 
... 


4-0 
4-0 


• • • 
 •  


1-0 
1-0 


• •• 


• •• 

• •• 


6-0 
6-0 


1 0-817 




1 


so 


... 


4-5 


• •• 


2-0 


 •• 


10 


7-5 


j 


M»y 


2 


60 


7-0 


30 


20 


20 


• « • 


• •• 


14-0 


[ 1-225 


1 


3 


60 


8-0 


4-0 


2-0 


2-0 


• •• 


 ■• 


16-0 


) 


June 


1 


60 


7*5 


2-5 


1-5 


1-6 


1-0 


• • • 


14-0 


1144 


Jidy 


1 


60 


5-0 


2-6 


2-0 


10 


10 


• •• 


11-5 


0939 


f 


1 


60 


4-5 


1-5 


1-5 


10 


10 


0-6 


10-0 


) 




2 


60 


5-0 


1-75 


1-5 


1-5 


1-0 


... 


10*75 


V 0-851 




3 


60 


4-75 


2-0 


1'6 


1-25 


1-0 


... 


10-6 


) 




1 


60 


4-6 


2-0 


1-0 


0-5 


00 


... 


8-0 






2 


60 


4-5 


1-5 


1-0 


1-5 


1-5 


. . • 


10-0 




September^ 


8 


60 


4-75 


2-0 


1-5 


1-0 


0-5 


... 


9-76 


} 0-785 




4 


60 


5-0 


1-75 


10 


0-5 


0-6 


... 


8-75 






5 


60 


4-75 


1-5 


10 


0-76 


0-5 


... 


8-5 




k 


1 


60 


4-76 


1-5 


0-75 


0-5 


0-5 


... 


8-0 


\ 


October 


2 


60 


4-5 


2-25 


1-5 


0-75 


0-75 


... 


9-75 


i 0-688 


1 


3 


60 


4-0 


1-25 


10 


0-75 


0-5 


... 


7-5 




/ 


1 


60 


5-0 


16 


1-26 


0-76 


0-6 


. .. 


90 


i 


SToTembers 


2 


60 


6-0 


2-0 


1-26 


0-75 


0-5 


••• 


10-6 


V 0-803 


( 


3 


60 


60 


1-25 


1-5 


0-5 


0-75 


... 


10-0 


j 


December 1 


1 
2 


60- 
60 


12-75 
12-5 


8-25 
8-5 


2-0 
1-5 


1-0 
10 


1-0 
l-O 


... 


20-0 
19*6 


1 1-614 



hi reference to the figures in the Table it may be mentioned, that M. 
BoQaaingaidt found that each successive tenth of the distillate contained 
iA the ammonia only of its predecessor, and that the whole appreciable 
VQiQonia was generaUy contained in the first four or five tenths. It is seen 
t^ this rule as to the proportional diminution of the ammonia in the 
fractional distillates is not well borne out in the figures of our Table ; and 
aUhongh we do not call in question the fact of this actual relationship in an 
ahsolutely uniformly conducted series, yet it would seem that in practice it 
ia not easy to attain it. Nor can we be much surprised at the dinerence in 
the amount of anmionia indicated m the ** total " column in cases of dupli- 
cate aaalyses, when we remember that each total is the sum of the amounts 



8 



obtained in fonr or five separate testings, in each of which the minimum 
error of obsenration is 0*25 of a septem of ammonia at 1^, and that it 
requires considerabfe practice, and some dexterity and accuracy of obser- 
vation, to avoid a greater range of error. Upon the whole, then, considering 
that in operating npon only a single litre of rain-water, the minimum error of 
observation, if any, will even with the most perfect manipulation geneiall? 
unonnt to 8 or 4 per cent, of the total ammonia contained in the water, aod 
further, that in any but the most practised and skilful hands the error may 
be much more than that supposed — ^indeed more than multiplied by the 
number of testings — ^we were led to abandon this second method also, not- 
withstanding its very obvious advantages so far as convenience and rapidity 
are concerned. These objections will of course apply with stiU greats 
force when rains containing less than the average amount of ammonia are 
operated upon, and especially in the case of the waters of springs and riveiB, 
tne average amount of ammonia in which would seem, according to H. 
Boussingault, to be vei^r considerably less than in any rain-waters. 

In subsequent experiments, therefore, we adopted the plan of operating 
upon several Utres of water in the first instance, reducing the bulk by sno- 
cessive distillations to one-half, until thus brought to a convenient amount 
for final distillaticn, and subsequent testing of measured pronortional amounts 
of the distillate in the manner described in reference to Method 2. This 
modification, we have since observed, was suggested by M. Boussingault 
himself, but it would seem he did not generally adopt it. In the next TBhle 
(III.) are given the results obtained by this Method 8, in which 8, 0, or 
12 lbs. of the rain-water were first operated upon, these quantities, as the 
case mi^ht be, being reduced to 24 ounces by successive distillations as 
stated above. This product was then finally distilled, and the distillate 
fractioned into quarters, the first three of which were separately super- 
saturated with the test-acid at 1^, and subsequently neutralized by the test- 
alkaU at ^^ 

Tablb III. 

Method 8.-^Distillati(»t8 to one-half, until rednced to 24 ounces, redistilled, 

and successive quarters tested. 



Tear 1854. 


1 


lbs. of 
rain-water 

1 


Septomg of ammonia at 1" in 


Ammonia 

mnifon 
raln-watsr. 


lit 
quarter. 


snd 
qoarter. 


8rd 
quarter. 


Total. 


ICoDths. 


January | 

Febmazy | 
Haroh... 
April*... 1 

May { 


1 

2 
1 
2 
1 

1 
2 
1 
2 


6 
6 
8 
8 
8 
12 
12 

12 
12 


12-5 
13-5 
6-5 
6-75 
8^5 
84-50 
86-25 
16-5 
16-26 


1-25 

0-75 

1-6 

1-5 

0^75 

1-75 

2*25 

1-26 

1-00 


1-5 

1-0 

1-25 

1-00 

0-26 

1-0 

1-0 

1-0 

0-75 


15-25 

15-25 

9-25 

9-25 

9-25 

87-26 

88-60 

18-75 

1800 


[ 0-779 

1 0*945 

0-946 

[ 0-967 

[ 0-469 



* April checked by Method 2. 



Water. 


TrtT" 




Tentni. 






TotaL 


tnilllnn- 




9nd. 


9rd. 


4th. 


"fitff. 




60OI8. 


9-0 


1-6 


0-5 


0-5 


0-5 


12-0 1 


0-980 



% 

A glance at the cohumiB of detail of this Table okarly illustrates the fact 
pointed oat by M. Bonflungaalt, upon which this method of detennining the 
unmonia in rain and other waters is based, namely, that in the case of very 
dilate solutions of the volatile alkali, nearly the whole of it passes over in the 
first portions of the distillate. We observe, however, that even where the 
*^ total '^ amoont of ammonia obtained from duplicate specimens of water is 
the same, or very nearly so, still the quantities det^mined in the correspond- 
ing fractional parts do not always agree so well. This would seem to indi- 
c^ that d« dS^epancy k due ^S^i^^Lrity in the di*^ 
to error of observation m the testing. It is trae, that this method of suc- 
cessive distillations is much more tedioos and troublesome than the method 
of small single distillations preferred by H. Boussingault ; and even with it, 
it would appear, as in one or two cases in Table III., that the difFerence 
between the amounts of ammonia determined in du|>lioate specimens of rain- 
water, may in practice be nearly as great in proportion to tne whole, as that 
which is assumed to be a not necessarily exceeded range of error in the 
method of small single distillations. Upon the whole, however, we ccmsider 
the modification involved in this Method 8, to be practically very important, 
and that this form of the process of estimation by distillation is much more 
api^cable to this delicate subject of inquiry than either of those which we 
have previously adopted. 

Before leaving the question of method^ it may be well to enumerate the 
calculated minimum proportions of error by the different methods, supposing 
that in Methods 2 and 8 equally with Method 1, this error would necessari^ 
only oocor onoe in a total estimation. This however is not the case ; for it is 
olmons, that in practice it might tend in the same direction in the estima- 
tion in each fraction of the distillate. It is on the other hand of course pos- 
sible, that the error, if it existed, imght be counterbalanced among the several 
fractions. 

Taking first Method 1, and supposing one-tenth of the concentrated acid 
product of 100 litres of water to be finally tested, this would, on the average 
of the amounts found in the rain at Kothamsted, contain 10 milligr.= 
0*1543 grain of actual anmionia. Assuming also, as was found in the prac- 
tice of the method, that the degree of accuracy easily attainable in the use of 
theacid and alkaUne test liquors at 10^, indicated 0*2 milligr.=0'OOdl grain 
of anunonia, this range of error would obviously amount to ^th, or 2 per 
cent, of the whde anunonia contained in the prodact tested : and it should 
he home in mind, that so far as the twtinff was concerned, there was no 
difficulty whatever in obtaining duplicate estimations which agreed absolutely 
together ; so that the amomit of error in a series was certainly not more in 
practice than that supposed. The difficulty with £his method however was, 
as before stated, in the management of such large distillations in glass 



In Method 2, that of M. Boussingault, 0*088 miDigr. of anunonia are sup- 

K^ to be determined, and the amount of water operated u^n to be 1 litre, 
e average amount of ammonia in 1 litre of the rains collected at 
Bothamsted is about 1 milligr., or 0*0154 grain ; so that the minimum limit of 
error wonld obviously be 8*8 per cent, of the wholle amount in such a case. 
The average quantity <rf ammonia per litre found by M. Boussingault in 
Uie rain of the open country does not exceed 0*8 mill^. ; in which case the 
nunimum error in estiimating to 0'088 miUigr. would amount to /^th, or 
rather more than 4 per cent, of the whole. In the water of rivers^ the average 
UQoont of ammonia, according to M. Boussinffault, was not quite 0*2 milligr. 
per litre ; upon which, determining only to the same amount as before, tlie 



10 

error might be between ^th and ^th, or about 16'5 per cent, of the whole. 
In spring-water^ &gain, M. Boussmganlt found generally only about half as 
much ammonia as in rivers ; in which therefore the snuJlest error in the de- 
termination in 1 litre only, would amount to about ird of the whole. 

According to Method S again, assuming that 12 lbs. of water (=about 
5it litres) were used, this, taking the average composition of the Bothamsted 
lains, would contain about 5|r milUgr. of ammonia ; and determining as we 
calculated to do, to 0*084 miUigr., the minimum error would thus be about 
■j-l^th, or about 0'6 per cent, of the whole. The probability of accuracy, 
therefore, so far as the process of liquid testing is concerned, would be 
greatly in favour of the third method, that of successive distillations. 

At the foot of Table III., however, is given the determination of anunonia in 
the rain of April 1854, according to Method 2, which indicates by the m^hod 
of small single distillation 0*98 ammonia per million of water, by the side of 
0*967, as ol^ained by the method of successive distillations ; fibres which 
coincide sufficiently to give confidence at least in the approximative truth of 
the results obtaincNi by the two methods. This brings us to a further con- 
sideration of the proportions of ammonia found in the rains collected at 
Bothamsted by the different methods, and of the actual amounts contained in 
the water which fell over a given area in different seasons ; and also to a com- 
parison of our own results with those obtained by other experimenters in 
other localities. 

Table IV. — Showing the proportion of ammonia per million rain-water, 
and the lbs. of ammonia m the monthly rain per acre, in different locali- 
ties and seasons, determined by different experimenters, and by different 
methods. 



Months. 


• 
Ammonia per million rain-water. 


lbs. of ammonia per acre. 


Paris. 


Lleb- 
frauen- 
berg. 


Bothamsted. 


Paris. 


Bothamsted. 


1851. 


1852. 


1853. 


1854. 


1851. 


1858. 1 1854. 

I 


Barral. 


Bouasln- 
gaolt. 


Meth. 1. 


Meth. S. 


Meth. 8. 


Barral. 


M0th.l. 


Meth. 2. 


Meth.S. 


Jannarj ... 
February... 

March 

April 

May 


2-98 
3-84 
1-08 
117 
8-88 


0*624 
0-445 
0-436 
1-494 
0-745 
0-721 


1-440 
0-812 
1-448 
1-399 
0-935 
0-821 


oiii 

1-225 
1144 
0-939 
0-851 
0-735 
0-688 
0-803 
1-614 


0-779 

0-945 

0-945 

0-967* 

0-469 


on 

100 
0-51 
0-46 
1-34 


0-77 
0-55 
0-55 
1-07 
0-95 
0-55 


'o-56 
0-47 
0-88 
0-96 
0-57 
0-38 
0-57 
0-87 
0-15 


0-32 
0-20 
0-11 
0-11 
0-46 


June 

Jtdy 


August ... 
September 
October ... 
KoYember . 
Deoember . 


Means... 


8-49 


0744 


1142 


0-979 


0-821 


0-81 

1 


0-74 


0-54 


0*24 


 By Method 2, 0-980. 



11 

In Table IV. are given, — 

The amounts of ammonia per million^ in the rain which fell at Paris 
during several consecutive months of 1851, as determined by M. Barral ; 
The proportions determined by M. Boussingault in the open country in 
Alsace, daring several months of 1852 ; 

The proportions in the rain which fell at Rothamsted during several months 
of 1853, in several cases determined both by Methods 1 and 2 ; also in that 
of several months of 1854 determined by Method 3. 
And in the second division of the Table, — 

The actual amounts of anmionia in lbs., contained in the rain which fell 
over the area of an imperial acre, in the case of each of the months experi- 
meoted upon by M. Barral at Paris, and by ourselves at Rothamsted. 

Comparing together the determinations of the ammonia per million of the 
ndns collect^ at Rothamsted in April, May, June, July, and August 1853, 
made by both the Methods I and 2 — ^in the one case dealing with hundreds of 
lbs. of rain-water, and in the other with only 80 or 60 ounces of it — ^the coin- 
ddenoes are such as to lead to the conclusion, that such discrepancies as there 
are, are due to manipulative difficulties and irregularities, rather than to 
erroneous principles inherent in the methods themselves. In the determina- 
tions for Mav and June, those made by method 2 are indeed notably below 
fchose made oy Method 1. But the obvious deviation from the regularity in 
the proportion of the ammonia found in the different fractional portions of 
the ctistillate, as seen in the detail of the determinations given in Table II., 
compared with that supposed by M. Boussingault to be so uniform, would 
Wad to greater confidence in the estimations made by Method 1. Confidence 
in the general principles of the various methods is, however, again afforded 
by a comparison of the determination made in the rain of April by Method 3, 
with that made in the same water by Method 2 as given at the foot of the 
Table ; the former giving 0*967, and the latter 0*980 parts of anmionia per 
million of the water. 

Tmsting, then, as we may do, in the general approximative truth of the 
rnolts obteined, we find, that taking all the determinations in the monthly 
lain collected at Rothamsted given in this Table, and which apply to that of 
fonrteen separate but consecutive months, the average amount of ammonia 
is almost exactly one part in a million of the rain. The average of Bous- 
Bingaolt's determinations in the open country of Alsace, and extending over 
wi months of the year 1852, from May to October inclusive, is seen to be as 
iKarly as possible |ths of the amount found at Rothamsted. The estima- 
tbna of M. Barral, on the other hand, in the rain collected at Paris during 
five consecutive months of 1851, fi*om August to December inclusive, give 
u average of nearly 3^ parts of ammonia in a million of rain-water ; and, 
in sobsequent experiments, M. Boussingault has found the ammonia in the 
iwu at Paris to be as great as that ob^rved by M. Barral. There can be 
no doabt, therefore, of the infiuence of a large city teeming with animal life, 
. Mid in which combustion of various kinds is so enormous, upon the propor- 
^of anmionia in the ambient atmosphere, and consequently on the amount 
of it which will be washed down in the rain. 

In what manner, however, locality, strictly so speaking, influences the actual 
unoont of ammonia from surface emanations or otherwise, in otherwise 
eqnallj open country, is still a qu^ion. But in reference to the proportion 
of it in a given amount of rain, it is at any rate interesting to observe, that 
^variations which we found in the amount of the ammonia in rain of dif- 
ferent but entire months, when considered in connexion with the registered 



12 

amounts of the fall, the direction of the wind, and the general characten of 
the weather, are perfectly consistent in kind with the results obtained hy M. 
Bonssingault in his special examinations of rain falling under different cir- 
cumstances, of the water of dews, of fogs, Ac. Thus, M. BousBinmolt 
always found a very obvious connexion between the amount of rain whidi 
fell in individual showers, and the proportion of ammonia in the water col- 
lected ; there being more ammonia per million of the water the less the 
amount of the fall. There was also much more anomonia at the conunenoe- 
ment of a shower than at the end of it, and after a drought than in continn- 
ously rainy weather ; though a comparatively short cessation of the rain was 
sufficient again notably to increase the proportion in the water collected. la 
the water of dews and fogs, again, he found the proportion of ammonia wna 
veiy high. 

From the above facte it would seem, that the proportion of anunonia 
found in the aqueous deposits from the atmosphere was greatly dependent 
on the amount of those deposits ; or, in other words, on the degree in whidi 
they diluted the soluble matters brought down by them from the atmosphere. 
Turning now more directly to the evidence of our own figures in reference 
to these points, it is at once obvious, that the period of the year has of itaelf 
no direct influence on the proportion of anmionia in the rain ; for we find 
that this is three times as great in the water of May 1853 as in that of May 
1854 ; the proportion found in the hitter being the lowest, and that in the 
former nearly tne highest, in our entire series of experiments. And that this 
was directly due in great part merely to dilution, is obvious from the fact, 
that whilst there was comparatively little difFerence in the actual amount of 
anmi(mia brought down over a given area in the two cases, vet with the 
small proportion of ammonia in the rain of May 1854, the fall was nearly 
tiiree times as great as in May 1853. The largest proportion of anunonia 
throughout the entire series was, however, in December 1853 ; and here it 
was that we had also the smallest fall of rain among the whole fourteen months 
submitted to experiment. But again, with this very large proportion of 
ammonia j0^ million of the ram^ there was during this month of December 
1853, as is seen in the second division of the Table, very nearly the smallest 
actual amount of ammonia washed from the atmosphere of any case in our 
series. Bearing in mind these facts, it will be only what would be expected, 
that we find the highest proportion of ammonia with prevailing northerly 
and easterly winds, and the lowest with prevailing southerly and wester^ 
ones ; but since the former are generally coincidait with a low, and the 
latter with a high amount of rain, any supposed material influence of the 
direction of the wind might probably much more properly be referred to the 
amount of the fall, or in other words, to the degree of dilution. 

In the same manner, since with storms we have frequently a considerable 
total fall, whilst with dews, mists, and fogs, the aqueous deposition is com- 
paratively small, any direct influence which the conditions of atmosphere 
involved in these states of the weather might have (apart from those inherent 
in the more general character of the season, or of local circumstances), either 
upon the formation, or emanation, or the slow or rapid condensation of 
ammonia, or upon the lessening of its amount by its conversion into nitric 
acid, is not at once obvious on the face of the figures ci the Table. Still, a 
careful consideration of our notes as to the general character of the weadier 
of the different months, taken in connexion both with the proporticm of 
ammonia in the water collected, and with the total amount of it broufl^ht 
down at different seasons over a given area of land, seems to indicate i£at 



13 

the prevalence of thniider«stonns has not of itself the tendency to increase 

the anuHUit of nitrogen brought down in the form of ammonia. And, even 

flqjpodng that the ^equent occurrence of storms during the warm^ months 

vere fonnd to be coincident with a large actual deposition of ammonia, it 

might still be a question wheth^ such a result were not dependent on other 

ehuacters of the season, or the conditions of the lower strata of the atmo- 

^diere, and their connexion with the surface, rather than upon those of the 

tngher strata, or the circumstances more directly leading to the development 

of the storms. At any rate it is worthy of remark, that in the month of 

May 1854, which was characterized by the occurrence of many, and some 

very heavy thunder-storms, and by three times the fall of rain of the cor- 

lesponding month of 1858, we have still a less total deposition of ammonia 

over a given area, than in either May 1853, or in the average of the other 

months, the rain of which was experimented upon : and, with regard to the 

influence, on the other hand, of the minor aqueous depositions upon the 

amoont of ammonia deposited, our notes and figures do not show any increase 

in the actual amount of ammonia so deposited, which could be attributed to 

them irrespectively of other circumstances, but rather that their more direct 

^ect is upon the proportion of the ammonia to the generally less actual 

unonnt of water, as already pointed out. Bub, whilst the proportion of 

ammonia per million of the water collected is thus seen to depend more on 

the mere amount of the fall than on the period of the year, it must obviously 

at the same time be mainly influenced by the total amount of ammonia 

actually brought down over a given area ; and this again would seem to 

have little direct or uniform connexion, either with the amount of the fall, or 

with the period of the year merely. Thus, as already stated, with three times 

as much rain in May 1854 as in Mav 1858, we have nearly the same, or even 

lather less total ammonia deposited, with the larger fall ; and again, com- 

puiiig the results of March and April 1853 with those of the same months 

of 1854, although it is true that in these cases we have the larger total 

amoont of ammonia brought down with the larger fall of rain, it is seen that 

tihere is in March 1854 only one-seventh, and in April 1854 only one-fifth, 

as much actual ammonia deposited over a given area as in the corresponding 

months of 1853. It is then, as above alluded to, upon other circumstances 

than either the amcmt of the fall or the period of the year, that the amount 

of ammonia brought down by the aqueous deposits from the atmosphere 

mainly depends. 

Taming to the more direct application of the figures to an important agri- 
wiltaral consideration, it may be stated that the amount of nitrogpn which 
oar experiments showed was brought down in actual solution from the atmo- 
sphere in the form of ammoma^ was adequate to supply but a small proportion 
^ the average annual amount of it contained in the produce of a continuously 
wunanured plot of ground. We must seek therefore for some other source 
o{ the nitrogen in our unmanured crops, than that which is brought down in 
win, and in the minor aqueous deposits from the atmosphere, in th^form of 
oamonia: and, without here entering into the question of the power of the 
soil, or of the plants themselves, to take up the ammonia or other nitrogenous 
wmpounds from the atmosphere, independently of the amounts which would 
te broT^ht down in direct solution in water, there seems to be good ground 
for sapposing, that another compound of nitrogen, namely nifrir acidy is a 
iQore liberal supplier of nitrogen to plants from atmospheric sources, than 
even ammonia itself. 
Although, as has been already mentioned, various experimenters have 



14 

detected nitric acid or nitrates in rain-water, yet it is to M. Barral that we 
are indebted for the first quantitative estimations of nitric acid in rain water 
which could lead to the supposition, that this is probably an important 
natural or climatic source of supply of nitrogen available for the growth of 
plants : and scanty as it yet is, still our daily increasing knowledge as to 
the occurrence and properties of ozom tends to enhance the probability of 
such a view. It was hence a chief object of this investigation to determine 
the quantities of the nitric acid as well as of the ammonia, in the rains col- 
lect^ at Rothamsted, and to estimate from these the sum of the nitrogen 
supplied by both, in relation to the average amount of it yielded in our 
unmanurea crops . Unfortunately, however, in consequence of the difficulties 
connected with the quantitative estimation of very small amounts of nitric 
acid, and especially owing to the existence of nitrogenous impurity in eaaie 
of the re-agents employed, though in proportions which for many purposes of 
analysis would be immaterial, the results arrived at on this head are by no 
means satisfactory or conclusive, or such as to justify a record of the nume- 
rical results obtained. 

The process adopted was as follows. Large quantities of the rain-water 
were evaporated with an alkaline carbonate several times to dryness, and the 
solid residue was carefully collected and weighed after diying at 212*^. The 
per-centage of nitrogen in this solid matter was then sought to be deter- 
mined by Dumas' direct- volume method of combustion with oxide of copper. 
Not only, however, were the results of duplicate analyses much more dis- 
crepant than they should have been, but the actual amounts of nitrogen indi- 
cated were in some cases so exceedingly higb, that suspicion was raised as 
to the purity of the re-agents employed ; and it afterwards appeared, that 
the oxide of copper, which had been j)repared from the nitrate, was not free 
from compounds of nitrogen which yielded it up in the combustion. But 
independently of the error which may have arisen from this cause, it must 
be admitted, that the process itself is not well calculated to attain the accu- 
racy requisite in such an investigation ; and in fact, that an accurate method 
for the determination of small quantities of nitrogen, or rather of nitric acid, 
is still a great desideratum. 

We repeat, then, that for the reasons stated, we refrain from recording the 
numerical results yet obtained in regard to the amount of nitric acid in the 
waters examined ; nor can we with full confidence rely even upon their 
general indications, in the discussion of the important questions, with a view 
to the elucidation of which this investigation was chiefiy undertaken, and to 
which we still hope to recur on some future occasion. After these pre- 
cautionary observations, however, we may mention, that if the indications of 
our nitric acid determinations may be trusted at all, it would appear that 
whilst the per-centage and actual amount of ammonia might be less in the 
rain of thunder-storms, and when thpre is a large fall of rain, the amount of 
nitric acid, on the other hand, is probably increased under the influence of 
storms. The results too would f urUier lead to the conclusion, that the amount 
of nitrogen brought down by the rain in the form of nitric acid, was con- 
siderable greater than that so deposited in the form of ammonia. On this 
point a^in, but without relying confidently on the indication, it may still be 
interestmg to observe, that with the very small amount of ammonia brought 
down in the rain of the winter and spring months of 1853-54, so far as they 
were examined, and which were succeeded by such an abundant harvest, the 
nitric acid results, taking them as they stand, show a much higher amount 
than usual in the months in question. It is true, that a study of our Me- 



15 

teoroI(^cal Tables is sufficient to show that other and more obvious and 
iDeasQiable climatic conditions materially conduced to such a favourable 
result. 

In conclusion, since there can be no doubt, that nitrates, ap{>lied as 
manures, greatly enhance the ^wth of plants by virtue of the nitrogen 
they contain, any amount of nitrc^en brought down from the atmosphere, 
in the form of nitric acid, must be considered to have an important in- 
fluence on vegetation. 



REPORT 



TO 



THE RIGHT HON; THE EARL OF LEICESTER, . 



ON 



EXPEBTMENTS CONDUCTED BY ME. KEAEY 



ON THE 



GROWTH OF WHEAT UPON THE SAME LAND 
FOR FOUR SUCCESSIVE YEARS, . 



AT HOLKHAM PARK FARM. 



By J. B. LA WES, F.R.S. 



LONDON. 



MDCCCLV. 



FROM THE 
JOURNAL OP THB ROYAL AORIGULTURAL SOCIETY OF ENGLAND. 

VOL. XVI., PART I. 



EXPERIMENTS ON THE GROWTH OF WHEilT. 



It has been proved by careful experiments that wheat can be 

grown for several years in succession upon *' heavy " land, and 

that by means of a proper supply of certain chemical substances, 

an average or even full agricultural crop, according to the season, 

may be obtained each year with certainty. But it is believed 

that there have been no experiments of the same kind carried on 

with accuracy and on a large scale, upon soils other than those of 

a comparatively heavy character. It is, indeed, not many years 

since the practice of removing from any land more than one 

corn crop in succession, was condemned as bad in principle ; 

and when we consider what was the amount of produce generally 

obtained in the second year^ it must be admitted that, under the 

circumstances then existing, the practice could not be easily 

justified. The increased sources, however, of artificial manures 

which have of late years been opened up, and more especially 

the comparatively larse and cheap supplies of that valuable agent 

ammonia, have furnished the agriculturist of the present day 

with a means of increasing, and in many cases of repeating, his 

com crops, which was not possessed by bis predecessor. To 

those heavy lands on which root crops were considered but as a 

necessary evil, these comparatively cheap and abundant sources 

of ammonia may be considered almost as great a boon as the 

application of the four-course system to the light soils by the late 

Eurl of Leicester. The limit, however, up to which the growth 

of com by means of artificial manures may safely be extended 

on different descriptions of soil, has yet to be fixed by the aid 

either of practical experience, or of more direct experiment. 

Leaving out of the question for the moment the important in- 
flaence of the subsoil in modifying the character and fertility of 
different descriptions of land, it may be said that, whilst in the 
** heavy " soil certain elements of fertility are comparatively more 
inexhaustible, though capable of liberation in but small quan- 
tities each year, — in the " Ught " soil, on the other hand, there 
is generally a less store of the elements of fertility, though 
they will yield up more rapidly those which are added to 
them in the form of manure. There is, however, an almost in- 
finite variety in the characters of our soils ; in some parts of 
our island we have those of the most opposite description within 
a short distance of each other ; and there are Lome whicii bo 
combine the qualities of ^' light " and ^* heavy " land, as to render 
it difficult on which side to classify them. There are others, 
again, which are decidedly light in character so far as the surface 
soil is concerned, but which possess in their subsoil a vast store- 
liouse of some of the native elements of fertility ; and hence whilst 

b2 



4 Experiments on the Growth of fVlieat, 

they are amenable to the same mechanical and other general 
management of the so-called light soils, they are more nearly 
allied to the heavy soils so far as the native resource of fertility 
is concerned. Whilst^ then, a broad distinction mast always 
exist between soils which can without injury be trodden by sheep 
in the wettest weather and those which under the same circum- 
stances will scarcely bear a foot to be put upon them — and it 
may be convenient to apply to them the current designations of 
"fty/d^" or "A^avy" accordingly — it must at the same time be 
remembered that these terms, as applied to a surface-soilj afford 
. a very imperfect indication of the probable native resources, and 
consequently of the capabilities of growth without deterioration 
of the respective soils. 

The soil upon which the experiments now to be recorded were 
made, is described by Mr. Keary as a ^' light, thin, and rather 
shallow brown sand loam,'' but ^' resting upon an excellent marl 
which contains a large quantity of calcareous matter." And he 
adds that he has invariably found these light sand loams toith the 
above subsoil '' to be most productive and grateful for hiffh Jarmr 
inff** In such a surface-soil, then, there will be combined the 
easily working qualities and the power of rapidly yielding up« 
manurial matter of the so-called *^ light" soils; whilst in its 
subsoil, we have much of the native resource of constituents 
and probably the power of absorption or retention of manurial 
matter also, of the so-called heavy soils. Still it is of the 
greatest interest, both in a scientific and in a practical point of 
view, to ascertain by actual experiment how far those chemical 
substances which are employed with success for the increased 
growth of wheat upon heavy soils, can be used with advantage 
upon those of different descriptions : and these experiments are 
therefore of considerable value towards filling up one gap in our 
knowledge on this subject. 

Here it may be suggested, that one very great desideratum at 
the present time is a few carefully-conducted experiments, not 
on too small a scale, to ascertain the result of the suc*ces8ive 
growth of wheat, on different descriptions of land, both an- 
manured and with a few well-selected artificial manures. How 
comparatively trifling would be the cost and trouble if one 
person only in each agricultural district in Great Britain would 
devote three acres of land in half-acre plots to the continuous 
growth of wheat for a series of years ; one portion being always 
unmanured, one manured with farmyard dung, one with minenJ 
manures only, one with ammoniacal salts only, one with both the 
minerals and the ammoniacal salts, and another with rape-cake ? . 
Yet such a simple series as this, carefully performed and accu- 
rately recorded, would in a few years furnish us with results 
which would be invaluable both in elucidating agricultural prac- 



Experiments of the Growth of Wheat. 5 

tices as they are, and in aiSbrding a sound basis for deduction, 
with a view to improvement according to the variations of soil 
and climate. 

It may be well to mention, that with the exception of a sug- 
gestion as to the nature and amount of the manures to be applied, 
and the supplying of some of them from the quantities prepared 
for the Rothamsted experiments, these experiments at Holkham 
have been entirely under the management of Mr. Keary. Thai 
they have been conducted with extreme care and accuracy is, 
however, to those accustomed to make agricultural experiments 
upon a lai^e scale, as obvious from the results recorded as if 
each operation had been witnessed. With a certain degree of 
experience it is impossible to be deceived in such matters ; and 
it may safely be stated that it is the injudicious arrangement, the 
careless performance, and the inaccurate record of agricultural 
experiments, that more than anything else retard our progress 
in scientific agriculture at the present time. 

It should further be remarked with regard to the land upon 
which these experiments were made, that previous to the intro- 
duction of the four-course system by the late Earl of Leicester, 
it had been considered too light for the growth of wheat. It has 
iiow for some years been farmed under that system ; it was clayed 
about 12 years prior to these experiments, and the crop imme- 
diately preceding them was white turnips, manured with farm- 
yard dung and guano, both tops and bulbs being drawn off the 
land. The experimental plots were half an acre each ; the 
manures were as follows, and were all sown in the autumn, 
except No. 4, which was sown in spring : — 

No. I. Always unmanured. 

No. 2. Mineral manures alone. 

No. 3. Ammonia-salts alone ; sown in the autumn. 

No. 4. Ammonia-salts alone ; sown in the spring. 

No. 5. Both the mineral manure and ammonia-salts. 

No. 6. Rape-cake. 

No. 7. Farmyard dung. 

The quantities per acre of the different manures are given in 
the Tables of the results which follow. 

The umrumured plot^ when once exhausted of the accumula- 
tions derived from the more recent previous manuring, will, of 
course, show the productive capability of the soil in a compara- 
tively normal state, in conjunction with that of the annual climatic 
yield of the atmospheric elements of growth ; and the results will 
provide a standard with which to compare the produce of the 
different manures. 

The mineral manure employed, provides a liberal supply of 
the alkalies, alkaline earths, and phosphoric acid ; and the pro- 
duce it yields compared with that of the other plots, s1iow« 



6 Experiments on the Chrowth of Wheot. 

whether the result of the cropping is to reduce the available 
supplies of such mineral constituents in the soil below that 
which is requisite to obtain the full benefit of the annual atmos- 
pheric supply of carbon and nitrogen, or whether it is the 
supply in the soil of the carbon or the nitrogen which is most 
exhausted. 

The use of amnumiacal salts aioney which provide nitrogen for 
the growth of the crop, shows whether or not the latent mineial 
wealth of the soil is more than sufficient for the annual atmos* 
pheric supply of available nitrogen. And the object of sowing 
one plot with ammoniacal salts in the autumn and another in the 
spring, was to show whether it was practically advantageous to 
sow such soluble manures in the autumn in so light a soil. 

The mixture of both the minerals and the ammoniacal salts 
shows, when the results are compared with those of each of these 
manures used separately — Ist, whether or not the annually avail- 
able native mineral supply of the soil, taken together with that 
in the manure, was not competent to a much greater amount of 
growth than the annual atmospheric supply of nitrogen was suffi- 
cient to produce? — ^and 2ndly, whether the amount of nitrogen 
supplied to the soil, when such a quantity of ammoniacal salts 
was used alone, was not in excess in proportion to the annually 
available supply of minerals from the soil itself? 

Rape^ake contains a large proportion of carbonaceous and 
nitrogenous organic substances, and some mineral matter ; and 
the nitrogen which was supplied in the quantity of it used was 
nearly identically the same, or perhaps rather greater in amount, 
than that in the ammoniacal salts of the other experiments. 

The Jarm-j/ard dung employed, was the product of yards in 
which bullocks were fed on turnips, with a moderate quantity of 
oilcake. In this farm-yard dung, there would be added to the 
soil every year a larger supply of every constituent than was 
contained in the increased wheat crop grown. 

In the three following Tables are given, the quantities of the 
different ingredients used as manure, and also the results obtained. 

In Table I. are given — The amounts per acre each year on 
each plot, of the dressed com, the offal com, and the straw.* 

In Table II. are given — The total produce of com for the four 
years collectively, and of the straw for the last three years, of each 
plot ; the average annual produce, both including and excluding 
the first year of the experiment ; the total increase by manure of 
corn in the four years, and of straw in three years ; the average 
annual increase by manure ; and in the last column, the amount 
of com yielded by each plot in the first year (1851) above the 
average of the succeeding years. In 

• It is much to be regretted that the straw was only weighed in the three last 
years, and that in no case is the weight of chaff and ** colder" or ** cavi^gs" given. 



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10 Experiments on t/te Growth of Wheat. 

In Table III. are given — The weight per bushel of the dressed 
com of each plot each year, and the average of the four years ; 
also the proportion of om\ com to 100 dressed corn in each case ; 
and the proportion -of com to 100 parts of straw. 

It is seen in the Tables that the experiments have alreadj 
extended over four seasons, namely, 1851-2-3-4. And althongh^ 
owing to the variable effects of climatic agencies according to 
the nature of the manurial matters in the soil, and the stage or 
tendency of growth of the plant depending on it, and to the litde 
that has yet been accomplished towards reducing the results of 
these complex influences within the rule and measure of calcula- 
tion, it is highly important that such experiments should be con- 
ducted through a considerable series of years, so as to get a fair 
average, and thus to exclude the influence both of recent accu- 
mulations in the soil, and of the climate of individual seasons — 
nevertheless, the results of these first, four seasons are of very 
considerable interest And they can hardly fail to afford further 
proof to the practical fanner as to what are (lie constituents which^ 
IB the general course of agriculture with rotation and home ma- 
nuring, and especially with a liberal growth of com, are likely 
to be most exhausted, and which therefore it is most important 
to supply by artificial manures if he would increase his breadth 
and produce of com. 

The first point to call attention to in the Tables is the last 
colunm of Table II., where we have given for each plot the num- 
ber of bushels of com obtained in the first season of 1851, over 
and above the average of the three succeeding seasons. It is seen 
that there is in every case a larger produce, by 14 to 20 bushels, 
or even more, obtained by the same manure in the first year than 
in the average of the following years. This result speaks well 
for the previous ^^ condition*^ of the land; and it is also very 
instructive as showing how useless, for the purposes of any general 
conclusions, are experiments with manures conducted over a single 
season only. It is in fact not until some of the elements of 
fertility, the due proportion of which to the others is compre- 
hended in the term ^^ condition," have been removed from the 
soil l^y the crop, that any safe deductions can be formed from the 
results of experiments with manures. Although it is possible 
that the field was not quite uniform as regards the accumulation 
from previous manures, it is at the same time not surprising that 
we should find the excess of produce in the first year greater on 
some of the plots than on the others, when it is remembered how 
very variable were the conditions of g;rowth provided by the 
experimental manures, and also how different would be the pro- 
gress or tendency of growth, and consequently the influence of 
the varying season, dependent on the varying supply of the ele- 
ments of growth by manure. It is however very unfortunate that 



Experiments on the Cfrawth of Wheat. 11 

the quantity of straw as well as corn was not ascertained in the 
first year ; for it is exceedingly probable that had it been so, 
there would hare been found to be a much greater uniformity in 
the excess of the^OM or total produce of the first year over that 
of the others, than is observable in that of the produce of cam 
alone. We now proceed to a study of the results of the individual 
manures; and in the course of it it will be rendered pretty obvious 
what was the nature of the unexhausted matters of previous 
manuring, which gave this greater produce in the first year of the 
experiment. 

Plot 1, which was unmanured, gave 39} bushels of dressed 

com the first year, 15^ the second, 2\i the third^ and 16f the 

fourth ; the average of the four years being 23^ bushels, and that 

of the last three years nearly 18 bushels ; which latter amount is 

nearly 22 bushels less than was obtained on the same plot in the 

first year. This average of 18 bushels per annum yielded after 

the condition of the land derived from recent previous manuring 

had been reduced by the first crop, is very nearly exactly that 

obtained annually on the much heavier soil of Rothamsted. This 

is a result which would scarcely have been anticipated ; and it 

shows that, at any rate for the present, the annually available 

supplies of minerals in the soil are fully equal to the not very 

widely differing atmospheric resources of the two localities, as 

judged both by the results obtained, and by a comparison of the 

meteorological registries of the several seasons. 

Plot 2, which was manured with salts of potash, soda, and mag- 
nesia, and super-phosphate of lime, gave 34i bushels of dressed 
com in the first year, rather more than 19 in the second, 19i in 
the third, and 18i in the fourth. It is seen, therefore, that there 
is only a variation of about 1 bushel during the last three 
years; and that the average of these last three years is about 
15 bushels less than was obtained in the first year. It is obvious 
that whatever were the elements of fertility present in the soil 
which were the source of the larger crop of the first year, they 
were in no way restored by the mineral substances supplied in 
the experimental manure. Again, comparing the produce of this 
mineral mixture with that of the unmanured plot, we find that 
taking the four years together there was actually rather more com 
obtained without manure than by the minerals ; the tendency of 
the latter being to increase the growth of straw, of which, taking 
the last three years together, there was about half a ton more 
obtained by means of the minerals. It is obvious therefore that 
mineral manures alone did little to remedy the characteristic 
exhaustion induced by the growth of the first crop of wheat, and 
that the annual mineral supplies of the soil were at any rate equal 
to the natural annual supply of nitrogen available for the growth 
of the crop. 



1^ 

12 Experiments on the Growth of Wheat. 

 In the next experiments (Nos. 3 and 4), the manure employed 
in each case consisted of 200 lbs. of sulphate of ammonia and 
200 lbs. of muriate of ammonia per acre ; but on Plot 3 they were 
sown in the autumn at the same time as the manures of all the 
other experiments, and on Plot 4 they were top-dressed in the 
spring. Looking to the columns of total produce (Table II.), we 
see that, taking the four years together, there is a difference of 
less than 2 bushels between the produce of the two plots, it being 
however rather in favour of the autumn-sown manure. The 
autumn-sown manure also gives on the average (see Table III.) 
a rather better weight per bushel. The produce of straw, taking 
together the tjiree last years (it not being weighed in the first), is 
nearly identical in the two cases, there being a difference only of 
8 lbs. in favour of the spring-sown manure. Upon the whole, 
then, the results are in favour of sowing these soluble manures in 
the autumn even in so light a soil. Comparing the produce of 
the different years by ammoniacal salts alone, we find that there 
is here again a fall in the produce of 18 bushels in the one case, 
and of 14^ in the other, from the first year to the average of the 
three last years ; and that there is afterwards something like a 
gradual reduction from year to year. It is obvious, therefore, 
that the amount of nitrogen supplied in this large dose of am- 
moniacal salts is in excess over the annually available minerals of 
the soil, which it would appear are becoming gradually reduced. 
That these, however, are nevertheless considerably in excess over 
those required by the natural supplies of nitrogen, is obvious from 
the fact, that whilst by mineral manures alone we got no increase 
of com whatever, and only a total increase of straw in the last 
three years taken together of about half a ton, the ammoniacal 
salts alone have given in the four years a total increase of 31 to 32 
bushels of com, and in the three last years of 2830 lbs. of straw. 
By the comparison, then, of the results of the mineral manures 
alone by the side of those of the ammoniacal salts alone, we have 
beautifully illustrated not only the nature of the characteristic 
exhaustion induced by the growth of the com, but we are also 
able to form a pretty clear idea of the actual degree or extent of 
that exhaustion, much more so at any rate than we should be by 
any analysis pf the soil. 

In Experiment 5, we have in the manure both the minerals of 
Plot 2, which gave no increase of com and but little increase of 
straw, and the ammoniacal salts of the Plots 3 or 4, which gave 
a considerable, though annually decreasing, amount of increase. 
The result of this mixture of both minerals and ammoniacal salts 
is to give, taking the 4 years together, from 53 to 54 bushels of 
com and a large quantity of straw more than is yielded by the 
minerals alone. This, then, is an annual average of 13 to 14 
bushels of com and an equivalent of straw due to the ammoniacal 



Experiments on the Growth of Wheat. 13 

salts. And since there is in the 4 years about 20 bushels more 
increase by the mixture of both minerals and ammonia salts than 
by the ammonia salts alone, it is obvious that the minerals of 
this last 20 bushels of the total 53 of increase were derived from 
the mineral manures employed. This is, therefore, conclusive 
proof that these minerals were supplied to the land in a form 
capable of being rendered available for the growth of the plants ; 
and it is therefore clear that the inability of the minerals when 
used alone, to increase the assimilation of organic constituents 
from natural sources, was not due either to their not containing 
soluble silica or other mineral matters required by the wheat- 
plant, or to an unavailable form of those constituents which were 
supplied. 

In the next Experiment (No. 6), the manure consisted of 
2000 lbs. of rape-cake per acre. As already explained, rape-cake 
contains a large amount of carbonaceous organic matter, a consi- 
derable quantity of nitrogen, and also some mineral matter. The 
quantity applied — namely, 2000 lbs. — was estimated to supply 
annually about the same amount of nitrogen (but in a different 
form of combination) as the ammoniacal salts in Experiments 3, 
4, and 5 respectively. It also supplied as much of the more im- 
portant minerals as would be contained in the increase of produce 
which was obtained by it. If, therefore, the total increase of 
produce obtained by the rape-cake should be pretty nearly the 
same as that yielded by the minerals and ammonia of No. 5, 
which contained, as has been said, nearly the same amount of 
nitrogen, but no carbonaceous oraanic matter^ we can only conclude 
that the latter in the rape-caJce has had little to do with the 
increase ; and, in fact, that this is attributable to the supply of 
nitrogen and minerals afforded by the rape-cake. A comparison 
of tbe results obtained by the nitrogen and minerals of No. 5, 
and by the nitrogen, minerals, and carbonaceous organic matter of 
No. 6, shows that, taking the average of the 4 years, the latter 
gives about half a bushel per annum more com, but about 90 lbs. 
less straw than the former. It is true that although the average 
produce of the minerals and ammonia of No. 5 and that of the 
lape-cake of No. 6 are so nearly identical, yet the produce of the 
two varies considerably in the individual years; but this can 
scarcely be wondered at, when it is remembered in what a very 
different form the nitrogen existed in the two manures, and also 
how differently the degree of their solubility, and consequently 
the stage or tendency of growth of tbe plant, would be influenced 
by equal conditions of climate. The average results are, how- 
ever, as already stated, all but identical, and we are therefore 
justified in deciding that in this experiment, as well as in the 
former ones, the increase of produce was measured by the amount 
of nitrogen supplied by the manure in a form available for the 



14 Eesperimerds on the Grouch of Wheat. 

gro^wth of the crop — provided, of course, the necessary minerals 
were not absent; and, further, that the carbonaceous organic 
matter is of itself of no practical utility as a manure for wheat. 
It may be- mentioned that this is a result precisely similar in 
character to that which has been obtained in the Rotbamsted 
experiments. 

The next and last Experiment is No. 7, in which 14 tons of 
farm-yard manure were applied per acre annually. It has already 
been stated that this amount of farm-yard dung would supply 
more of every constituent than would be contained in the increase 
of crop due to its employment. It would contain, in fact, from 
3 to 4 tons of carbonaceous organic substance, whilst the annual 
increase of produce did not contain 1 ton of such matter. The 
minerals in the dung would also very far exceed those in the 
increased produce yielded, and its nitrogen would be greater in 
amount than that supplied in the ammoniacal salts of Experi- 
ments 3, 4, and 5, or in the rape-cake of Experiment 6. There 
would, however, be this difference as r^;ards the nitrogen — 
namely, that whilst that which was supplied in the ammoniacal 
salts would be the most readily dissolved in the soil, that in 
the rape-cake would be so in a less degree, though much more 
rapidly in a light soil than in a heavy one. Part of the nitrogen 
of the dung too would also be rendered easily available, but that 
portion which entered into the composition of the straw would 
probably require some years before the whole was liberated 
and applicable for the growth of the crop. The result of the 
experiment with the dung is, that we get an average annual in- 
crease by it of about lOi bushels of com and 1300 lbs. of straw, 
which is less by nearly 3 bushels of com and about 150 lbs. of 
straw than was obtained by the rape-cake. The weight i>er 
bushel of the corn grown by the dung was, however, on the 
average about i lb. heavier than that by the rape-cake, which will 
account for part of the deficiency. Now, as we have seen by the 
other experiments, that neither minerals alone nor carbonaceous 
organic matter, had any influence in the increase of the crop, but 
that wherever there was a supply of nitrogen in the manure there 
was always a very considerable increase, we have every reason to 
conclude that it was the amount of nitrogen liberated from the 
dung in a form applicable by the plants which fixed the limit to 
the increase of produce obtained by its use. And in confirma- 
tion of this conclusion, it may be recalled to mind how very 
amall would be the amount, both in the carbonaceous organic 
matter and of mineral matter, in the increase of produce obtained 
in proportion to the amount of either of them supplied by the 
farm-yard manure. It is tme, that neither is the amount of 
nitrogen contained in the increased produce of wheat ever equal 
to that supplied in the manure which yielded that increase ; but 



Experiments en the Growth of Wheat. 15 

it must be remembered that^ besides any liability to loss by 
drainage, to which all might be subject, the nitrogen, in several 
of its forms of combination, is also volatile, and may be exhaled 
into the atmosphere and lost, but this is not the case with the 
nodneral constituents of manure. 

Upon the whole, then, a careful study of the various experi- 
ments has proved, — 

That the soil, even with the most unusual and very exhausting 
process of carrying off the land the total grain and straw of 
several successive corn-crops, after a root-crop which had also 
been drawn from the land, still contained a larger annual available 
supply of minerals than the annual natural supplies of other con- 
stitnents, nitrogen or carbon, were adequate to turn to account ; — 

That the excess of the annual supply of minerals in the soil 
over that required to appropriate the natural resources of nitrogen, 
is proved, by the effects of ammoniacal salts alone, to have been 
equal to the further growth, during 4 years, of about 32 bushels 
of wheat, or an average of about 8 bushels per annum ; — 

That beyond the increased annual produce which the supply 
of minerals in the soil was adequate annually to provide when 
nitrogen was not wantmg, the average capabilities of the climate 
were competent for the maturing of a still greater produce, if 
additional minerals as well as the ammoniacal salts were pro- 
vided ; and, in that case, from once and a half to twice as much 
com was grown as the natural supplies of nitrogen, even with a 
most liberal supply of minerals, were sufficient to produce ; — 

That carbonaceous organic matters (such as are contained in 
TMe-cake and farm-yard dung) are of themselves of little or no 
enect in increasing the growth of wheat. 

We can now have little difficulty in deciding to what accu- 
mulated elements of growth to attribute the higher ^' condition '* 
or greater fertility of the first year, as compaied with the suc- 
ceeding ones. Mineral manures alone have had no effect in 
restoring the fertility which was exhausted by the first experi- 
mental crop. Ammonia alone gave a produce of several bushels 
more than the unmanured plot in the first year, and has, on the 
average of the last 3 years, given half as much again of produce 
as either the unmanured or the mineral manured plot ; and the 
addition of minerals to this ammonia has restored a further incre- 
ment of the lost fertility. In no case, however, have the artificial 
manures of subsequent years entirely restored the original fertility : 
or rather, in no case (with it is true a difference of season), has 
there since been a produce quite equal to that of the unmanured 
space of 1851. From the above facts it is obvious that in the 
first year there existed in the soil a larger supply both of avail- 
able minerals and of available nitrogen than in any of the 
succeeding years ; but that in the first year there existed accu- 



16 Experiments on the Chrowth of Wheat. 

mutated available minerals in the soil considerably in excea of 
the accumulated nitrogen available for the growth of the crop ; 
and that it was the limited amount of the latter, and not of toe 
former, which fixed the limit to the amount of produce of the 
unmanured plot in the first season — that is, so far as the greater 
amount of it that year waa due to manuiial constituents inde- 
pendently of the climatic variations of the different seasons. In 
a word, the practical- fact is elicited, that by the growth of com 
in a soil which has been cultivated in an ordinary manner with 
rotation and home-manuring, the supplies of available minerals 
are not nearly so soon exhausted as those of the available nitrogen. 
In fact, the soil has been reduced from a comparatively high 
wJieat-growing condition to a very low one, by the exhaustion of 
its immediately available floating stock of nitrogen ; and it was 
in this very low wheat-^rounng condition^ notwithstanding that the 
mineral elements of fertility still existed in it in such an excess 
in relation to the natural resources of nitrogen, as was sufficient 
for an increase of crop during a succession of years, provided 
only that nitrogen was artificially added to it. 

What, then, is the lesson to practical farming which these 
experiments should teach us ? It will not be supposed, that be- 
cause .it is here shown that in a cultivated soil of a comparatively 
light character an increased growth of wheat may be obtained 
over a continuous series of years by the use of nitrogenous 
manures alone — that hence rotation and home-manuring should 
be abandoned, and that corn-crops should be grown continuously 
by means of nitrogenous artificial manures? There cannot, 
however, be a doubt of the legitimacy of the inference from these 
and other experiments, that provided the land receive in a course 
of years a due share of the home manures derived from feeding of 
horses and other stock on the farm, the mineral supplies of the soil 
will be amply sufficient to sustain an increased and even repeated 
growth of com, by means of nitrogenous artificial manures, con- 
siderably beyond that which is recognised by the leases or the 
current practices of the day ; and a further assurance that the 
necessary minerals are not likely to become deficient, under the 
judicious adoption of such an increased growth of com, is to be 
found in the fact that there are few really large sources of nitro- 
genous manures which do not, at the same time, bring upon the 
land a considerable amount of some of the more important 
minerals also. 



Loudon : Printed bj Wiluam Clowes and Sons, Stamford Street, 

and Charing Croes. 



REPLY 



TO 



BARON LIEBIG'S 



"PRINCIPLES OF AGRICULTURAL CHEMISTRY." 



BY 



J. B. LAWES, F.R.S., F.C.S, 



AND 



Dr. J. H. GILBERT, F.C.S, 



DECEMBER, 18B8. 



LONDON: 
PRINTED BY W. CLOWES AND SONS, STAMFORD STREET 

AND CHARINQ CROSS. 
1865. 



REPBINTED BY SPOTTISWOODE A CO., NEW-STBEET SQUARE. 

1898. 



FROM THE 
JOURNAL OF THfi ROTAL AGRICULTURAL BOOIBTY OF ENGLAND, 

VOL. XVI. PART II. 



#X/ VV\' VNi^WV^\«\/\/\/\/ WX/A/^^\/ S^'S^ ^\/ \^ V \/\/% 



ON 



SOME POINTS CONNECTED 



WITH 



AGRICULTURAL CHEMISTRY. 



On more than one occasion we have expressed our high sense 
of the important services rendered to the furtherance of fixed 
principles in agriculture by Baron Liebig. We have particu- 
larly called attention to the fact that the masterly review of 
the then existing knowledge on the subject contained in his 
work entitled *' Organic Chemistry in its Applications to Agri" 
euUure and Physiology ^'^ and publidied in this country in 1840, 
had, more than any other circumstance, given that stimulus and 
direction to chemical inquiry, in connexion with agriculture, 
which has characterised the subsequent period. It was naturally 
to be expected, however, that the evidence to be derived from 
the inquiry that had thus been incited, would, in the progress of 
time, necessitate the modification or extension of the expression 
then given to the relations of science with practice. 

In his third edition, indeed, published in 1843, Baron Liebig 
himself announced, in his Preface, that he had, in the years 
which had elapsed between that edition and his first, endea- 
voured to make himself '* acquainted with the condition of prac- 
tical farming, and with what it requires, by a journey through 
the agricultural districts of England and Scotland " — and also in 
that interval instituted a long series of experiments on the subject 
in the laboratory at Giessen, with the sole object of giving a 
finner basis to hia ^' exposition of the causes of tiie advantageous 
^^ults attending the practice of rotation of crops, and also of 

▲ 2 



4 Agricultural Chemistry. 

effectually banishing all doubts concerning their acenracy." 
He goes on to say, **/ am nowj for the first time^ since 
the completion of these laboars, in a sitnation to give a simple 
and determinate expression to my views of the origin of 
animal excrements, and of the cause of their beneficial effects on 
the growth of all vegetables." And he adds : " Now that the 
conditions which render the soil prodiLctive, and capable of afford' 
ing support to plants, are ascertainedy it cannot well be denied, 
that from chemistry alone all further progress in agriculture is 
to be expected." 

After this announcement, it would have been unfair to Baron 
Liebig, to have attributed to him in any discussion, the views of 
his earlier editions, on points wherein he had modified them in 
his later ones. With this feeling, whenever we have, in our varions 
papers, pointed out wherein it appeared to us that Baron Liebig's 
doctrines, as applied to agriculture as it is, required either modi- 
fication or correction, we have invariably discarded all reference 
to his earlier published views, and assumed as our starting-point 
those given in his later editions, for which he claims a firmer 
basis and a greater certainty. 

Baron Liebig, however, as it would appear, without having 
at that time read our own statement of our views, but only that 
summary of them given in a few lines by the late Mr. Pusey, 
devoted, in his 'Letters' published in 1851, a note of some 
pages to a notice of our conclusions as so given. He expressed 
himself thus : 

" With regard to the experiments of Mr. Lawes (the best authority, accord- 
ing to Mr. Pusey), they are entirely devoid of value, as the foundation for 
ffeneral conclusions, with a knowledge of our experience of the effects of 
fallow, and of production on the large scale, it requires all the courage 
derived from a want of intimate acquaintance with the subject to assert, 
that certainly ammonia is peculiarly litted for grainy and phosphorus for 
turnips, and that manuring with straw is probably advantageous for 
turnips/' — Letters, 3rd edition, p. 480. 

Now, although Mr. Pusey was, perhaps, more competent than 
any other practical agriculturist to speak to the wants of British 
farming, yet the terms used by him were by no means those 
which we ourselves should have employed ; and it was obviously 
nnfair in any writer to take his statement of our views, rather 
than that which we have ourselves given of them. 

But, nevertheless, so fiiUy satisfied were we of the conclu- 
sions intended to be expressed by Mr. Pusey — in the langtmge 
and in the connexion in which we have ourselves given them 
in our Papers — that we felt it incumbent on us to reply to 
such emphatic condemnation of our experiments and conclusions, 
by one whose opinion, if founded on fair and careful criticism, 
should have so much weight as that of Baron Liebig. Hence 



Agricultural Chemistry, 5 

it was that, in 1851, we published in this Journal, in a Paper 
entitled ^ Agricultural Chemistry y espedaUy in relation to the 
Minerai Theory of Baron JUsbigj an answer to his strictures above 
referred to. 

It is in reply to our Paper, just mentioned, that Baron Liebig, 
in the spring of the present year, published a short treatise 
entitled " Principles of Agricultural Chemistry^ with special refer- 
ence to the laie Researches made in Mugland^^ which has been 
circulated very freely in Germany, France, England, and America, 
Nearly the whole of this treatise is devoted to a critical examina- 
tion, in some form or other, of the experiments made at Rotham- 
sted — of the opinions to which, by these and facts relating to 
other districts, we have been led — and of our representations of 
the author's views, as distinguished either from the expression 
which he claims himself to have given to them in his former works, 
or from that which he would at present assign to them. He 
accuses us at once of not having read^ of misunderstanding, and of 
misstating his views. He asserts that we have disproved that 
which we intended to prove ; that we have proved that which we 
intended to disprove ; and, in fact, that cmr results in aU points 
confirm the truth of his doctrines, as announced in his works. 

These are certainly rather serious charges. But not only 
have they been made under the incitement of controversy, by 
Baron Liebig himself, but they have been deliberately endorsed, 
in a Preface, by Professor Gregory, the English editor of Baron 
Liebig's work, in a manner so inconsistent with the obvious 
facts and justice of the case, that one can hardly be otherwise 
than amused at the zealous partisanship which could alone 
aocount for his extraordinary assurances. But this is not all. 
Periodicals, unconnected either with chemistry or agriculture, 
have, upon the credit of the high authorities referred to, taken 
for granted the truth of their statements; and thus they have been 
echoed, unexamined, through the general press. It is only due, 
therefore, both to ourselves, and to the large body of intelligent 
agricalturists who have from time to time expressed their con- 
fidence in the conclusions emanating from Rothamsted, and who 
have in so marked a manner acknowledged their sense of the 
value of the experiments upon which they are founded, that 
we should fully vindicate, not only the opinions themselves, but 
our integrity and honour in dealing with those of others, which 
have thus been called in question in high quarters. 

We cannot but regret, on many grounds, that it should have 
|>ecome necessary to treat of our important subject much more 
^ the controversial form than we had at first designed. It 
will, however, be our endeavour to turn the course which has 
^^ been forced upon us to as good account as possible, bv 



1 



6 Agricultural Chemistry. 

making tbe execution of this part of our task the occasion of 
bringing before our readers a review of the published views, not 
only of Baron Liebig and ourselves, but of distinguished authori- 
ties both in this country and abroad, who have pronounced on 
the points involved. 

The plan we propose is as follows : — 

1st. To show, by copious quotation, both from Baron Liebig's 
previous writings and our own, what really have been the pub- 
lished opinions and doctrines of the former, and how far our own 
statements of those opinions and doctrines are justified by his 
own words. 

2nd. To show how his views have been understood and inter- 
preted by other writers than ourselves, not only in this country, 
but in Germany, France, and America, 

Srd. To examine Banln Liebig's Btatementa and criticisms of 
our experimental evidence and conclusions regarding the growth 
of whsat and turnips ; and to adduce further evidence and argu- 
ments in support of the conclusions which we really have main- 
tained on the points involved. 

4th. To illustrate, by condensed summaries of an immense 
mass of experimental results, some prominent points of interest 
connected with the action of manures on the different crops of 
rotation^ and with the chemical circumstances involved in faUoWy 
and a rotation of crops itself 

And lastly, throughout our observations we shall take occasion 
to point out the material admissions which are to be discovered 
in the newly published opinions of Baron Liebig ; which show, 
^ that, notwithstanding there are still points of difference between 
us, we have now at least the sanction of his almost unequalled 
sagacity for the judgment which we have pronounced on certain 
points, as distinguished from the opinions which he formerly 
so prominently advocated on the same. 



Firstly, then, as to the consistency of our statements of Baron 
Liebig's doctrines, with his own statements of those doctrines. 
One of his chief complaints against us on this head, is in re- 
ference to a sentence occurring in one of our Papers; we 
quote it below. But we must here call attention to the in- 
accurate manner in which Baron Liebig makes his quotations ; 
not only in the case immediately under consideration, but in many 
others, some of which we shall have occasion to point out. A 
similar want of accuracy is observable in his quotations both 
from Professor Wolff and Mr. Way, in the course of this same 
controversy. The portion which we give in brackets, thus [ ], 



Agricultural Chemistry. 7 

occurs in the original, but is not given by Baron Liebig in his 
apparently continuous quotation from our Paper. 

"In the course of tJiis inquiry, the whole tenor of our resultfl [and aUo qf 
mformation, derived from inteUigent agricuUwtd friends, upon every variety 
of land m Oreat Britain'] has forced upon ub opinions different from those of 
Professor Liebig on some important points; and more especially in relation to 
his so-called ' mineral theory/ which. is embodied in the following sentence, 
to be found at page 211 of the third edition of his work on Agricultural 
Chemistry, where he says, ' The crops on a field diminish or increase in exact 
proportion to the diminution or increase of the mineral substances conveyed 
to it in manure.' " — Journal of the Royal Agricultural Society of England^ 
ToL xiL part i. p. 2. 

With regard to the omission made by Baron Liebig in his quo- 
tation, we will only here observe how important is such an omis- 
Bion, when one of the main objections which Baron Liebig alleges 
against our conclusions is, that they are founded upon our own 
experiments alone^ and without any consideration of what would 
happen on other soils and in other localities ! 

Baron Liebig complains that the sentence which we have 
quoted as embodying his own doctrines, has been detached 
from its natural connection with a series of sentences, and thus 
a meaning given to it quite different from that intended by 
its author. In proof of this, he professedly gives the sentence 
in question with its context, and also comments, to which we 
shall call attention. But here again we must beg the notice of 
the reader to Baron Liebig's inaccurate mode of giving a quotation, 
for the purposes of controversy, within unbroken inverted commas. 
We give the sentence, from p. 210 of the 4th edition of Baron 
Liebig's ' Chemistry in its Applications to Agriculture and 
Physiology^* from which he himself professes to quote. The 
first two portions which we give between brackets, thus [ ], 
occur in the original, but are omitted in Baron Liebig's quotation ; 
and the word " the " so inclosed, is given in the quotation, but 
does not occur in the original : — 

" Hence it is quite certain, that in our fields the amount of nitrogen in the 
CTX)p8 is not at all in proportion to the quantity supplied in the maaure, and 
that [the soil cannot oe exhausted by the exportation of products containing 
nitrogen {unless these products contain at the same time a large amount of 
mineral ingredients), because the nitrogen of vegettUion is furnished by the 
atmosphere and not by the soil. Hence a^o] we cannot augment the fertility 
of our fields [or their powers of production'jf by supplying them with manures 
rich in nitrogen, or with ammoniacal salts alone. The crops on a field 
diminish or increase in exact proportion to the diminution or increase of the 
mineral substances conveyed to it in [the] manure** 

The reader will perceive more clearly, as we proceed, the 
importance of the omissions made in the quotation of the 
above sentence, bearing, as they do, both upon the question of 
what were Baron Liebig's opinions as to the dependence of 



8 AgricuUural Chemistrtf. 

plants upon the cUmaspherej and ik^ upon the sail, for theif 
nitrogen in dgriouUure as distinguished fi-om normal vegetation — 
and upon the distinctions which he seeks to draw, between fer- 
tility (as implying duration) and iimnediafs production merely. 

But upon the sentence in the altered form, Barou Liebig 
says : — 

** In the sentences just quoted from my book, the produce of the land k 
compared with the proportion of nitro^nous matter^ indusiTe of minend 
substances, supplied in the manuret and with the amount of mineral conatir 
tuents, inclusive of nitrogenous substances, supplied m the manttre, 

'* The words ' by ammoniacal salts alone * and ' m the manurif ' show that I 
never thought of excluding carbonic acid and ammonia in the manure. Ac- 
cording to Mr. Lawes*s mistaken notion of my meaning, I ought to bave said, 
omitting the word manure, that * on the contrary the fertility of the land 
rises and falls with the amount of mineral substances supplied to tt,* But this 
I have not said. 

" The meaning of these sentences in my work is this : ' that amnwrnacal 
salts alone ' have no effect ; that, in order to be efficacious, they must be aocom- 
panied by the mineral constituents, and that the effect is then proportional to the 
supply, not of ammonia, but of the mineral substances,^ — Principles of Afgrir 
cultural Chemistry p. 64, 55. 

Now, in reference to Baron Liebig's third paragraph of com- 
ment, it may be observed that, inasmuch as in the original he 
speaks of " manures rich in nitrogen" as well as *' ammoniacal 
salts alone,*^ the statement that he meant merely '' that armnonicLcai 
salts alone have no effect," is obviously quite inadmissible ; whilst 
the introduction of the definite article " the " is the only founda- 
tion for the meaning claimed by Baron Liebig that he only in- 
cluded manure containing both nitrogenous matter and mineral 
substances — and that he did not speak of the fertility of the land 
rising and falling ^' with the amount of the mineral substances 
supplied to it." But he himself admits in another page {Prin- 
ciplssy 115) that he did refer to manure generally, whether 
" mineral manure, guano, poudrette, farmyard manure, Ac," 

Whatever may have been the meaning of Baron Liebig in the 
sentence we have quoted, or whatever the interpretation which 
he would now give it, we shall presently make such full quotation 
from the same edition of his work, and from other publications, 
and also from other authorities, as will enable the reader to jadge 
for himself — not only what was the obvious meaning of the sen- 
tence in question, but what has been the interpretation of that 
sentence, taken in connection with many others in his writings, 
by others of his readers than ourselves. 

Before doing this, however, we will give a single illustration ot 
how fundamental was the change made by Baron Liebig from 
the first edition of his work, to the third and fourth and subse- 
quent publications ; as by this means, the reader will not only be 
prepared to form a right judgment of what we shall have after- 



Agricultural Chemistry. 9 

wards to quote, bnt the unscrnpnlous nnfaimess of an anony* 
mous article in the Journal of the Highland Society will be fully 
apparent. We have already shown how distinctly, in the Pre- 
face to his third edition, Baron Liebig admitted a change and 
perfecting in his views since the first. And yet, incredible as it 
may appear, our Northern critic admittedly makes his quotations 
by which to fasten the accusation of misrepresentation upon our- 
selves, from Baron Liebig's first edition, and from his * Prin- 
cipled,' lately published in the course of the controijersy ! 

One of the quotations made by this critic, with a view of 
showing that we have misrepresented Baron Liebig, in attributing 
to him an inadequate appreciation of the importance of avail- 
able nitrogen vMhin the soil itself for the growth of some of our 
most important crops in agricultural quantity^ he takes from the 
Urd edition, as given below. We give by its side the sentence 
as it occurs in Baron Liebig's third and fourth editions ; and 
the capitals are our own, to draw attention to the words altered 
from the earlier edition to the later ones. 

** CultivHted plants receive the " Cultivated plants receive the 

same quintity of nitrogen from the same quantity of nitrogen from the 

atmosphere as trees, shruhe, and other atmosphere as trees, shrubs, and other 

wild plants ; Birr this is not suffi- wild plants ; and this is quite suffi- 

CIBST FOR THE PURPOSES OF AOBICUL- CIENT FOR THE PURPOSES OP AORICUL- 

UTRI.*— l«i Editum^ p. 86. turb."— ^rrf and 4th Hditions, p. 64. 

Notwithptanding, then, that in his third and fourth editions, 
Baron Liebig exactly reverses the opinion held in hie first, on 
the very point in reference to which the sentence is brought 
against us — yet it is from the first edition that our critic quotes ! 
In this slight alteration, too, we have a key to the fundamental 
change in Baron Liebig's views in regard to the capability of a 
liberal supply of the constituents proper to the soil itself — the 
viiTieral constituents — to enable plants to obtain from the atmo- 
sphere " sufficient " nitrogen for an agricultural amount of crop. 

We shall now assume that we have given evidence enough of 
a change in Baron Liebig's views from his first edition to his 
later ones, to show that it is quite inadmissible to quote from his 
earli^ in judgment of our representations of his later opinions. 
The following is the manner in which we have ourselves repre- 
sented those opinions in reference to the point referred to by the 
cntic in the Highland Society^s Journal, and also by a writer in 
the Saturday Bevieiv of November 10, 1855, et seq. : — 

** J^ractical agriculture consists in the artificial accumulation of certain 
^^ituents to be employed either as food for Tnnn or other animals, upon a space 
^f ground incapable of supporting them in its natural state. This definition 
p^^culture IS, I think, important, as distinguishing English agriculture at 
*wt.,fTona the system pursued in various parts of the world, where the popu- 
^^tion is Binall and the laud of little Tidue, viz., of taking only the natural 



10 Agricultural Chemistry. 



produce of the soil, without any effort to increase it, and in time abandoning 
it for a soil ae yet undisturbed. If Liebig had sufficiently considered thii 
distiDCtion, he would not have assumed that certain substances employed as 
manures are uf little value, because plants and trees, in their natural state, are 
capable of obtAining them in sufficient quantity for their use." — Journal of 
the Royal Agricultural Society of England, voL viii. part i. p. 227-8. 

'*The atmosphere and the virgin soil heing originally the exclusive sources, 
the former of the ' oryanic^^ and the latter of the ' inorgamc ' or ' fftineral ' 
constituents of plants, it has been supposed that the amount of produce 
which a given space of <rround would yield must depend upon its richness in 
thiise substances proper to itself, namely, the mineral constituents ; and that 
these being supplied in full quantity, according to the indications of the 
analyses of the ashes of the crops it is wished to grow, the atmosphere would 
always prove an ample available resource for the more peculiarly vegetable 
matterp. It will be readily understood that on such a view as this^ economy 
in Hgriculture would be attained by a very different cours<) of practice from 
that reauired were it to be shown tbat cultivation should effect an artificial 
accumulation in the soil of those constituents primarily derived from the 
atmosphere, rather than of such as more especially belong to ita own oon- 
stitutioD. 

** The theory referred to has led to the analysis of the ashes of a great 
many agricultural crops, and upon the data thus obtained (rather than upon 
a conpiderHtion of the reouirements actually induced by an artificially 
enhanced vegetation, or of tlie real source and ilestination oi the constituents 
under a course of practical agriculture), recommendations to the sgriculturist 
have been founded, the validity of which it was desirable should be tested 
by actual experiment, as well as by the presumed dictates of experience." — 
lb. vol. viii. part ii. p. 535. 

'' It is true that, in the case of vegetation in a native soil, unaided by art, 
the mineral constituents of the plants being furnished from the soil, the 
atmosphere is found to be a sufficient source of the nitrogen and carbon ; and 
it Lr the supposition that these circumstances of natural vegetation apply 
equally to toe various crops when grown under cultivation that has led 
Baron Liebig to suggest that, if by artiticial means we accumulate within 
the soil itself a sufficiently liberal supply of those constituents found in the 
ashes of the plant, essentially soil constituents, we shall by this means be 
able in all capes to increase thereby the assimilation of the vegetable or atmo- 
spheric constituents in a degree sufficient for agricultural purposes. But 
agriculture is itself an artificial process; and it will be found that, as regards 
the production of wheat more especially, it is only by the accumulation 
within the soil itself of nitrogen, nafiira/fy derived from the atmosphere, 
rather than of the peculiarly soil-constituents, that our crops of it can be 
increased. Mineral substances will indeed materially develop the accumulsp 
tion of vegetable or atmospheric constituents when applied to some of the 
crops of rotation ; and it is thus chiefly that these crops become subservient 
to^ the growth of the cereal grains ; but even in these cases it is not the con- 
stituents, as found cuUectively in the ashes of the plants to be grown, that are 
the most efficient in this respect ; nor can the demand which we find thus 
made for the production of crops in ^^cu/^ura/^u/infiVy be accounted for by 
the mere idea of supplying the ocft^a/ constituents of the crop. It would 
seem, therefore, that we can only arrive at correct ideas in agriculture by a 
close examination of the actual circumstances of growth of each particular 
crop when grown under cultivation." — lb. vol. xii. part i. p. 6, 7. 

But there is another eentence in one of onr Papers in which we 
have sought to indicate Baron Liebig's views, against which he 
strongly protests. It is as follows : — 



Agricultural Chemistry, 11 

" In conclusion, then, if the theory of Baron Liebig simply implies that 
the growing plant must have within its reach a sufficiency of the mineral 
coDstitoents of which it is to be built up, we fully and entirely assent to so 
evident a truism ; but if, on the other hand, he would have it understood that 
it IB of the mineral conf>tituents, as would be colUctively found in the ashes of 
the exported produce, that our soils are deficient relatively to other consti- 
tuents, and that, in the present condition of agriculture in Great Britain, * we 
cannot increase the fertility of our fields by a supply of nitrogenized pro- 
ducts, or by salts of ammonia alone, but rather that their produce increases or 
diminishes, in a direct ratio, with the supply of mineral elements capable of 
assimilation,' we do not hesitate to say that every fact with which we are 
acquainted, in relation to this point, is unfavourable to such a view.'' — lb, 
vol. zii. ptft i. p. 39. 

The comments Baron Liebig makes on this sentence are as 
follows : — 

"In the first part of this quotation Mr. Lawes admits the truth of the «ch 
ealled mineral theory ; in the second I find ttoo erroneous statements the con" 
tamed d^usion of which I can no longer tolerate,^ — Pfinciples, p. 115. 

In the first part, then, of this comment by Baron Liebig, we have 
the important admission, that the so-called "Mineral Theory" 
— as he would now have it umlerstood — " simply implies that the 
growing plant must have within its reach a suflBciency of the 
mineral constituents of which it is to be built up." And if 
it should be shown by the copious quotations which we have yet 
to make from Baron Liebig's former writings, that his earlier 
" Mineral Theory," and as applied to agriculture^ was far more 
correctly indicated by the latter portions of our sentence, which 
Baron Liebig tells ns he " can no longer tolerate " — if this be 
shown, we may congratulate ourselves on a very material limita- 
tion of his formerly promulgated opinions. We have here also the 
admission, that " we fully and entirely assent " to such a " Mi- 
neral Theoiy," as "simply implies that the growing plant 
must have within its reach a sufficiency of the mineral consti- 
tuents of which it is to be built up." And in this latt.er admis- 
sion Baron Liebig must surely be conscious of a rebuke to him- 
self, for the per\'ading insinuation throughout his criticism of our 
views, that we have ignored the necessity of mineral constituents 
to plants. Thus he says — 

''It is not easy to understand how Mr. Lawes could deduce from his results 
tbecoDclusion * that nitrogenized manures are pectdiarly adapted fttr the culture 
ofvheatf'' since such manures can only produce a favourable result if certain 
FdmUnary conditions, which Mr. Lawes has entirely disregarded, be fulfilled." 
--ft. p. 79. 



And 



again — 



"Now, every one would suppose from this, that Mr. Jjawes thought that 
ue use of ammonia enabled us to dispense with that of mineral manure, 
loanded on the knowledge of the composition of vegetable ashes, and that 
^li«M, the ashes or mineral constituents, might be replaced bj ammonia." . . . 



12 Agricultural Chemistry. 

'< For if Mr. Lawes admit, that the mineral constitueiits are indispensable to 
plants, how can be maintain that these very mineral constituents are replace- 
able by ammonia, that is to say, that by means of ammonia we can altogether 
dispense with them ? '' — lb. p. 89. 

Baron Liebig is perfectly well aware, that the sentences he 
refers to, presupposed certain ^^ prelirninary conditions^'^ and had 
reference simply to the source of the mineral constituents of 
plants in the ordinary coarse of agriculture. For those who 
have not read our Papers, however, we may say, that any such 
insinuation as that here intended by Baron Liebig, is empha- 
tically condemned — not only by special sentences, such as those 
quoted above, but by the whole tenor of our writings — as Baron 
Liebig himself is well aware, if ever he have read them. 

But to return to Baron Liebig's comments on that state- 
ment of his doctrines which he " can no longer tolerate,** he 
says : — 

*' The concluding sentence ascribes to me the assertion that the produce of 
land is proportional to the supply or diminution of the available mineral con- 
stituents. TJtis I have never eaidJ'* — lb. p. 116. 

Compare this with the quotation already given : — 

" The crops on a field diminish or increase in exact proportion to the 
diminution or increase of the mineral substances conveyed to it in manure." — 
Agricultural Chemistry^ 8rd ed., p. 212. 

Again Baron Liebig says : — 

** With regard to the previous sentence, T find in my work only one yaaaa^i^ 
in which I speak of the land of England in the sense understood by Mr. 
Lawes." — iVtnctjp/«, p. 116. 

And in reference to this point he also says : — 

*' It is not difficult to refute the opinions of another, if we ascribe to him' 
assertions which he has never made. 

'' It never occurred to me to assert that the land of Great Britain was defi- 
cient in the substances which are found together in the ashes of the crops raised 
on it, or that, on a soil naturallj fertile, rich crops might not be obtained for 
several successive years, 6y the use of ammoniacal salts alone" — ^p. 116. 

Baron Liebig denies, then, that he has addressed himself to 
the resultant wants of agriculture as practised in Oreai Brifoin — 
that he has ever maintained that the fertility of our fields in- 
creases or diminishes in a direct ratio with tlie supply of mineral 
elements capaljle of assimilation — or that, it is in the mineral 
constituents^ as collectively found in the ashes of the exported 
produce^ that our soils are deficient relatively to other consti" 
tuewts. 

We will now examine the foundation of these several assertions. 
And first — in order to show, that it was not only AGRICULTURE (as 
distinguished from normal vegetation), but that it was agriculture 



Agricvltwral Cliemistry. 13 

as fractised in Great Britain^ on which Baron Liebig has 
addreBsed the English public in his various writings, we say : — 

That the title of one of his publications is — * Organic 
Chemistry in its ApplicoMons to Agriculture and Physiology.* 

That of another is — 'An Address to the Agriculturists of 
Great Britain, on the Principles of Artificial Manuring.' 

And of another — ' On Artificial Manures.' 

That in the preface to the third and fourth editions of his 
main work, he states them to be put forth, after having endea- 
voured to make himself " acquainted with the condition of 
practical farming, and with what it requires, by a journey 
through the agricultural districts of England and Scotland." 

We were justified then in concluding that Baron Liebig put 
forth his doctrines not only as applicable to normal vegetation^ 
but to agricuUure^ and to the existing condition and wants of 
agriculture as practised in OreaJt Britain. We will now show, 
by quotations &om his works, whether we have mis-stated his 
yiews on the following important points, viz. : — 

The dependence of our cultivated plants — whether graminaceous 
or leguminous — upon atmospheric sources for their supply of 
nitrogen. 

The direct dependence of the amnmint of produce on the available 
mineral food of plants within the soil. 

The nature of the restitution to be made ^^from without " in a 
course of practical agriculture. 

He says (4th edition, as already quoted) : — 

" Cultivated plants receive the same quantity of nitroj^n from the atmo- 
Bphere as trees, shrubs, and other wild plants ; and this is quite sufficient for 
tkt piurpose$ of affrictdfure,^ — p. 64. 

** It is obvious, therefore, that there is no deficiency of atmospheric food 
for the plants of these regions, and there can be none for our oton cultivated 
pUmtsr—^, 167. 

** Are the fields of Virginia, the fields of Hungary, our own cultivated piantSy 
not able to receive it from the same sources as the wild-growing vegeta- 
tion? Is the supply of nitrogen in animal excrements a matter of absolute 
indifference f OB DO ws obtaik is oub fields a quaivtitt of the coir- 

RITUENTS OF THE BLOOD, ACTUALLY CORBESPONDTNe TO THE BXTPFLT OF 

AXMoiraA P *' — p. 206. The capitals are Baron Liebig's own. 

" Hence it is quite certain, tnat in our fieldSf the amount of nitrogen in the 
crops is not at all in proportion to tbe quantity supplied in the manure, and 
that the soil cannot oe exhausted by the exportation of products containing 
utrogen, (unless these products contain at the same time a large amount of 
minoral ingredients), bioauee the nitrogen qf vegetation ie furnished by the 
ttmotflkerej and not by the M^i/."— p. 210. 

*^ Is fertility not ({uite independent of the ammonia conveyed to the eoil t 
If ws evaporated unne, dried and burned the solid excrements, and supplied 
to oar land the ealts of the urvnCf and the aehes of the solid excrements^ would 
not the cultivated plimtsgrovmon it — i}i<^graminMsandleg\im,inos<B — obtain 
their carbon and nitrogen from the same sources whence they are obtained by 
^ gnminett and leguminosss of our meadowd P There can scarcely be a 



14 Agricultural Chemistry, 

doubt with rpffard to thM^ qiwstiona, when we uniie tJie information fumitktd 
by science to tkttt suppliod hy the practice of Offrirulfure,*' — p. 203. 

These then are Baron Liebig's opinions, in his later editions, 
as to the equal independence of plants — wild or cultivated — 
graminaceous or leguminous — of assimilable nitrogen provided 
within the soil. We do m t mean to say, that there are not both 
facts and opinions recorded in Baron Liebig's writings, totally in- 
compatible with the series of sentences which we have quoted, 
or have still to quote. We leave the inconsistency to be explained 
by Baron Liebig himself. 

We must here beg the reader's attentive recognition of the fact, 
that the subject of which both Baron Liebig and ourselves are 
speaking is agriculture, not normal vegetation — ^that we treat of 
** cultivated ** land, not a mere sand-pit, or other circumstances 
(agriculturally speaking abnormal), under which every mineral 
constituent of the plant has to be artificially provided. It must 
not be forgotten that there are here certain " preliminary condi^ 
tions" namely, a cultivated soil — one, therefore, which is supposed 
to contain a certain amount of the necessary food of plants ; but 
in a more or less actively fertile condition, according to the 
original composition of the soil itself — its state of mechanical 
and chemical degradation — and the home-manuring and cropping 
to which it has been subject. What then are the circumstances, 
with these *^ preliminary conditions" under which produce in 
agricultural quantity is to be obtained ? Baron Liebig says : — 

" The ammonia of animal excrements exerts a &vourable influence only 
because it is accompanied by other substances necessary for its converswn into 
the constituents of the blood. When these conditions are furnished with am- 
monia, the latter becomes assimiUted. But when the ammonia is absent frotn 
the manure, the plants extract their nitrogen from the ammtmia of the air ; to 
which it is again restored by the decay and putrefaction of dead animal and 
vegetable remains." — p. 210, 211. 

'' But, at the same time, it is of great importance for agriculture, to know 
with certainty that the supply of ammonia is unnecessary for most of our cul- 
tivated plants, and that it may be even superfluous, if only the soil contain a 
sufficient supply of the mineral food of plants^ when the ammonia required far 
their development wtU be furnished by the atmosphere,^ — p. 212. 

Referring to the mineral elements of the soil, Baron Liebig 
says: — 

** If these elements are present in sufficient quantity, and in appropriate 
proportions, the soil contains the conditions which render f A/' jp/onf capable of 
absorbing carbonic acid and ammonia /rom the atir, which is an tnexlumstihU 
storehouse for them^ and renders their elements capable of being assimilated 
by their oivanism . The agriculturist must, therefore, conjlne himself to givi ng 
to the fiela the composition necessary to the development of the plants which 
he intends to grow ; it must be his principal task to bupply and restore all the 
elements required in the soUy and not only one, as is so frequently done ; the 
ingredients of the air, carbonic acid, and ammonia, the plants can, in most 
ca-ses, procure tcithout man*8 interference: he must take care to give to bis 



Agricultural Chemistry, 15 

field that physical condition which renders possible and inoreaj^es the assimi- 
latioD of theae ingredients 6y the plant; he must remove the impediments 
which diminish their eiiiect.*' — Address — * On the Principles of Artificial 
Manuring^ — p. 16. 

'* The duration of the fertility of a field depends on the amount of the 
mineral aliments of plants contained in it, and its productive power for a 
given time is in a direct proportion to that part of its composition which 
possesses the capacity of being taken up by the plant." — Address, p. 10. 

'* Practice in agriculture has taught us that the amount of vegetable 
natters on a given surface increases with the supply of certain substsncesy 

WHICH WSRE OBTGINAL 00N8TITT7ENTS OF THE BAUE SURFACE OF THE SOIL, 

and had been removed from it by means of plants. The excrements of men 
and of animals arise from plants ; they are exactly the materials which, 
during the life of the animal, or after its death, obtain again the same form 
that they possessed as constituents of the soil. 

*' We know that the atmosphere does not contain these materials, and tlat 
it does not replace them ; we know further that, by their removal from the 
soil, an inequality of production is occasioned, and, finally, even a want of 
fertility; but that, btf the restoration of these materials, the fertility may be 
tusUtined and even increasedJ'^ — ith Edition, p. 164. 

" The fertilising poiaer of manure can be determined by weight, as its effect 
it in a direct ratio to its amount in the mineral elements of the food of 
plants,^ — Address, p. 11. 

The above quotations show what was the relative importance 
attached by Baron Liebig to the nitrogenous and the mineral 
constituents of manure respectively ; and how far he has been 
misrepresented on this point, by the quotation from him of 
which he so much complains ; namely, that " the crops on a 
field diminish or increase in exact proportion to the diminution or 
VMTease of the mineral substances conveyed to it in manure." 

We shall now proceed to point out what were the means in- 
sisted upon by Baron Liebig, as necessary to the maintenance and 
increase of production of cultivated land ; by which a judgment 
may be formed, whether " it never occurred " to him " to assert 
that the land of Great Britain was deficient in the substances 
which are found together in the ashes of the crops raised on it." 
Baron Liebig says : — 

^Is it conceivable, that a rich fertile land, with a flourishing trade, 
which has for centuries exported the products of its soil in the form of cattle 
snd of com, can retain its fertility, ii the same trade do not restore to its 
land, in the form of manure, the constituents abstracted from it, and which 
ctnnot be replaced by the atmosphere P In such a case, would not the same 
&te await this land as that which befel Virginia, upon the soil of which 
wheat and tobacco can no longer be cultivated ? " — ith Edition, pp. 164, 165. 

Speaking of phosphate of lime and the alkaline phosphates, 

lie says: — 

** An enormous quantity of these substances indispensable to the nourish- 
Dent of plants, is annually withdrawn from the soil and carried into great 
^<)wn8 in the shape of flour, cattle, &c. It is certain that this incessant 
femoyal of the phosphates must tend to exhaust the land and diminish its 
capabilitjr of producing grain. The fields of Great Britain are m a state of 
F^asne exhaustion from this cause, . . . .^ — Letters, p. 522. 



16 AgricttUural Chemistry, 

** If it were poRsible to restore to the soil of England and Scotland the 
pbosphatee which during the last fifty years have been carried to the sea by 
the Thames and the Clyde, it would be equivalent to manuring with millionii 
of hundredweights of bones, and the produce of the land would increase one- 
third, or perhaps double itself, in five to ten years.** — lb. p. 52.*^. 

^' If a nch and cheap source of phosphate of lime and the alkaline phos* 
phates were open to England, there cau be no question that the importation 
of forei^m com might be altogether dispensed with after a short time.'* — 
lb. p. 624. 

" It has been mentioned in the preceding part of the chapter, that animal 
excrements may be replaced in agriculture by other materials containing 
their constituents. Now, as the principal action of the former depends upon 
their amount of mineral foodf so necessary for the growth of cultivated plants, 
it follows, that we might manure with the mineral food of wild plants, cr, 
in other words, with theib ashes ; for, these plants are governed by the 
same laws, in their nutrition and growth, as cultivated plants themselves. 
Thus, these ashes might be substituted for animal excrements ; and if a proper 
selection were made of them, we might again furnish our fields with all the 
constituents removed from them by crops of cultivated plants.** — 4th JEdition, 
p. 182, 183. 

Speaking of the exhaustion of alkalies by the growth of wheat 
and tobacco in Virginia, he says : — 

''Almost all the cultivated land in Europe is in this conditionJ" — 4tk 
EditvoUy p. 118. 

" It is also of importance to know, that the rule usually adopted in France 
and in Germany of estimating the value of a manure according to the 
amount of its nitrogen, is quite fallacious, and that its value does not stand 
in proportion to its nitrogen. 

" By an exact estimation of the quantity of ashes in cultivated plants^ 
growing on various kinds of soils, aud by their analysis, we will learn those 
constituents of the plants which are variable, and those which remain con- 
stant. Thus also we will attain a knowledge of the quantities of all the 
constituents removed from the soil by different crops. 

** The fanner will thus be enabled, like a systematic manufacturer, to have 
a book attached to each field, in which he will note the amount of the 
various ingredients removed from the land in the form of crops, and there- 
fore how much he must restore to bring it to its original state of fertility. 
He will also be able to express in pounds weight, how much of one or of 
another ingredient of soils he must add to his own land, in order to increase 
its fertility for certain kinds of plants. 

** These investigations are a necessity of the times in which we live ; but in 
a few years, by the united diligence of chemists of all countries, we may 
expect to see the realisation oi these views ; and by the aid of intelligent 
farmers, we may confidently expect to see eAtabli^ed, on an immovable 
foundation, a rational system of farming for all countries and for all soils." — 
p. 212, 218. 

Speaking of the importation of phosphoric acid into Great 
Britain in the form of bones, in ten years, he says : — 

"To have increased the fertility of the fields in the right proportion, 
800,000 tons of potash ought to have been added to the 1,000,(X)0 tons of bones 
in a suitable form." — Address^ p. 13. 

'' The fabrication of a manure, equal in its composition and efl^ts to the 
solid and fluid excrements of animals and men, seems to me one of the most 
essential demands of our time, more especially for a country like England, 



I 



AgrkuUural Chemistry, 17 

in which, from various circumstances, a rational Agriculture, without a supply 
of manure in some shape or other /ro/n without y seems nearly impossible." — 
Ih., p. 24. 

Now, on what principles, and by what constituents, does 
Baron Liebig propose to provide England with a manure ^^from 
tmihovJt^^ equal in its composition and effects to genuine guano, 
and to the solid and fluid excrements of animals and men ? He 
goes on in the same page to say, " The following salts may be 
regarded as the essential constituents of a powerful manure ap- 
plicable to all descriptions of soil." He then enumerates under 
this head, all the constituents indicated by analysis in animal 
manures, including, not only the mineral constituents, but 
flWMTkwiia, decaying i^egetable matter, &c. But, immediately after- 
wards, speaking of the mineral substances^ he says : — 

'* These are the substances which together give fertility to the soil; but 
although each of them may, under certain circumstances, — namely, where 
the soil is defective, or where it is not indifferent to the plant to take up one 
instead of the other, as, for instance, may be the case with soda instead of 
potass,— increase the fertility, no one of them can be regarded as manure, 
according to the common meaning of the word, for the simple rea<>on, that 
only all of them, in certain proportiorUf will fulfil the purpose for which the 
oommoQ manure is applied. This purpose is the restoration, or an increase 
of the original fertility, and By manure we must replace all the constituents 
of the plants which have been taken away in the harvest, or which are 
emtained in the plants which we are desirous to cultivate.*^ — lb., p. 26. 

Having thus stated the principle upon which a manure ^om 
mthouty and to replace guano and the solid and fluid excrements 
of animals and men, should be compounded, he says : — 

''What, then, are the constituents of the soil which we remove by the 
>traw, aeedi), tuberculous roots, stalks, &c., of our plants of culture? It is 
obrioiis that we must know these firsf, in order to restore them in sufficient 
quantities. To this we answer, by giving the analysis of the ashes oj plants 
^^ their KedsP ! ! 

After this overwhelming amount of evidence on the point — 
culminating as it does to an almost exact reflection of what we 
have assumed in our Papers to be the Mineral Theory of Baron 
Liebig as applied to agriculture — after all this evidence from 
kis own writings, we need scarcely ask : — 

Is there in the sentence of our Paper, of which Baron Liebig 
80 much complains — is there, we ask, in that sentence, that of 
^Mch he should say : — 

In it—" I find two erroneous statements, the continued dif- 
fusion of which I can no longer tolerate " ? 

Or is he jnstified in asserting that he has never said — ** That 
fcae produce of land is proportional to the supply or diminution 
oi the available mineral constituents " ? 

That—*' I find in my work only one passage in which I speak 
^f the land of England in the sense understood by Mr. Lawes " ? 

B 



18 Agricultural Cliemistry. 

That — " It is not difficult to refute the opiuions of another, if 
we ascribe to him assertions which he has never made " ? 

And that — " It never occurred to me to assert that the land of 
Great Britain was deficient in the substances which are found 
together in the ashes of the crops raised on it," &c. ? 

Or, need we further ask — ^Where is the Oxford version * of the 
** Mineral Theory," — namely, that " it throws upon the air, or 
upon the ingredients of the manures which a/re organic in their 
origin^ the task of furnishing nitrogen to the plant" — where 
is there any trace of this version of the " Mineral Theory," in 
the overwhelming amount of Baron Liebig's own definitions of 
his peculiar doctrines which we have been quoting ? 

Secondly. We will now show how Baron Liebig's so-called 
*' Mineral Theory " has been understood by other writers than 
ourselves, not only in England, but in Germany, Prance, and 
America. 

Dr. Muspratt, formerly a pupil of Professor Liebig at Giessen, 
now Professor of Chemistry at Liverpool, and a son of the 
gentleman of that name who undertook the manufacture of 
Baron Liebig's manures in this country, commenting on a lecture 
by Mr. Karkeek, in which he had detailed the results of some 
experiments with Baron Liebig's manures, says : — 

'' It has long since been established that when the inoi^ganic ingredients 
are all present, and in siifficient quantity, the carbon and nitrogen the plants 
can assume from the azV without the interference of the farmer, if the land be 
in that physical condition which is requiflite for the assimilation of the ammonia 
and caroonic acid present in the atmosphere.*' — Mark Lane Express, March 
1, 1847. 

Mr. Karkeek, in the course of his reply to Dr. Muspratt, thus 
indicates what he understands is the doctrine of which Dr. 
Muspratt was the representative : — 

" Taking, then, these three experiments as they stand, and well knowing 
that the Trewithen meadow had been very highly manured for a long time, 
while the contrary was the case in the other two instances^ I consider that I 
was not much out of the way in stating my opinion that the failure of Ldebig's 
manure was the consequence of a want of sufficient quantity of azotised and 

Sb should have been reported) carbonised matters in the soil ; and whatever 
r. Muspratt may think to the contrary, notwithstanding I have such high 
authority to contend with, yet from the practice which I have had in observing 
the effects of various kinds of artificial manures during the past five vears, I 
am quite satisfied that the inorganic elements are of very little value as a 
manure for plants without a corresponding supply of the organic. Indeed I 
am of opinion that plants have neither the power of assimilating the inorganic 
elements in the soil, or the organic substances from the atmosphere in each a 
dngree as to enable the farmer to grow twenty tons of swedes to the acre, unless 
they are also supplied with a proper quantity of carbonaceous and azotised 
substances at the same time.'' — Mark Lane Express, March 22, 1847. 

* See Saturday Revierc of Nov. 10 and Dec. 1, 1856, et seq. 



1 



Agricultural • Chemistry. 1 9 

Again — The Council of the Royal Agricultural Society of 
England undertook a series of investigations as to the composi- 
tion of the ashes of agricultural plants, with the object, in ac- 
cordance with the doctrine of Baron Liebig, of ascertaining the 
manures required to restore to land its productive capability lost 
by the removal of previous creps, or to prepare it for the sub- 
sequent growth of this or that agricultural plant. In the course 
of this inquiry their able chemist actually provided recipes on 
the nrinciple alluded to. . But, as we well know, his own judg- 
ment and sagacity led him to doubt the sufficiency of the plan 
submitted to him to answer the ends supposed, long before his 
task had been concluded. Nor need we remind the reader, that 
investigations of a similar kind, and instigated by the same sug- 
gestions, have been made in many of the European laboratories 
with the same object ; or further, that an immense number of 
manure-making schemes have arisen in England, Germany, 
France, and America, professedly founded on the principle 
alluded to. 

In the * North British Agriculturist* of November 7, 1855, 

the editor thus defines Baron Liebig s views : — 

''Now, according to Liebig, ammonia is always afforded by the atmosphere 
in excess, while mmeral matters, if not always, are at all events generally 
deficient in the soil ; hence his inference is, that in order to increase the crop, it 
i» only necessary to add the latter. He does not assert that ammonia is use- 
leas : on the contrary, he would have everj farmer to add it to his soil, and 
that abundantly, if he hapjpens to possess it ; but if he proposed to lay out a 
certain sum of money in the purchase of manures, he would counsel him to 
expend it on mineral matters^ and trust to the atmcfsphere for the ammoma, 
^hich he believes may be obtained from it in quantity more than sufficient for 
iht largest crop which it is possible to obtain" 

Professor Johnston, in a lecture delivered at the York 
Meeting of the Royal Agricultural Society, in 1848, says : — 

" A third opinion adopted by many, and extensively acted upon by some, 
lAjtliat plants obtain all their or^ranic matter directly from the airy and derive, 
and therefore require, only mineral matter from the soil* " — Jour, Roy, Agr, 
Soc. Eng., vol. ix. part i., p. 223. 

And, in a note to which attention is drawn by the star given at 
the end of his sentence. Professor Johnston gives the very sen- 
tence from Baron Liebig, which we are ourselves so much com- 
plained of for quoting, thus : — 

^ l^e crops on a field diminish or increase in exact proportion to the dimi- 
nution or increase of the mineral substances conveyed to it in manure. — 
IMgr 

I^ France — M. Boussingault, whose competency to judge of 
anch matters is second to none in that country, and whose high 
character and authority as a philosopher and an agricultural 
chemist no one will doubt, thus indicates both his understanding 
and his opinion of Baron Licbig's doctrine — 

B 2 



20 Agricultural Cliemisiry, 

** The view which assumes that the saline substances which manures con* 
tain, are their only really useful constituents would lead to advising farmers 
to bum their manure heaps in order to diminish the carriage, always such air 
inconvenience and so costly. I question whether this advice would ever be 
followed. Moreover, careful obeervHtion has shown that the org-anic sub- 
stances in manure exert a very marked effect. Thirty square metres of in- 
fertile clay soil were manured with farm- jard roRnurei and yielded a very good 
crop of oats. By the side of this, on an equal surface, were spread the ashes 
(the salts therefore) of an equal quantitv of the same manure ; by so doing 
tlie produce was not sensibly increased.' — Eamomie Rurale^ vol. ii. p. 81-2 
(Translated). 

Another able French writer, M. Puvis, in his * Traits des 
Amendements/ says (we give the passages translated)- — 

'' Humus, in a soluble state, would be the peculiar food of plants, and 
would, moreover, furnish them with an incessant supply of carbonic acid, as 
the illustrious chemist of Giessen himself admits, though nt the same time he 
calls in question the necessity of animal manures.^' — p. 423. 

*' The illustrious chemist of Giessen, having formerly admitted, in common 
alike with practical men and theorists, that atnmonia is an essential and ne- 
cessary constituent of manure, now regai-ds it (ammonia) as one of the con- 
stituent principles of atmospheric air, and maintains that plants will derive it 
thence according to their requirements, as they do carbonic acid.'' — p. 623. 

*' He then goes on to express a hojte that the time may come Vihen saline 
matters in small bulk will he substituted for animal manures.'* — p. 624. 

** In his new system he would almost exclude nitroyenf which however 
practical ex:perience teaches us to look upon as one of the most active agents of 
production,** — p. 624. 

*' Since the chemist of Giessen, Liebig, has proposed to replace the manure 
heap by small quantities of saline suhstmtces, and nas himself set the example 
of the sale of these substances, propositions for new manures have rained upon 
us in all parts of Europe ; in France, much more than elsewhere, manutac- 
turing processes have risen up in all directions, to replace stable and other 
powerful manures by substances either in powder or in the liquid state, of a 
bulk fifty or one hundred times less than even the emallest quantities of 
manures which experience had sanctioned. Since 1842 we may reckon eighty- 
six patents of inventions for new manures, and all promise the highest pro- 
ductiveness.*' — p. 627. 

'' The chemist of Giessen has adopted the fundamental principle of the system 
of Duhamel, namely, that plants derive from the atmosphere all the volatile 
principles which enter into their composition; but considering that plants also 
contain fixed mineral principles which are not found in the atmosphere, and 
that successive crops would soon deprive the land of these substances necesaary 
to vegetable organisation, he has thought it necessary to add to thie system of 
Duhamel, as a necessary condition, that we must give to the soil the minerai 
substances according to the composition of the crop that we wish to produce. 
Convinced of the justice of his theory he thought to profit by it, and accord- 
ingly artificial manures modified to suit the nature of the soil, and the kind of 
crops, were sold under his name in Germany and England ; the name of the 
distinguished chemist ensuring in these two countries a great number of 
trials, to which nothing in general was wanting but success." — p. 682. 

" After the failures resulting from the use of the Liebig manures they were 
soon abandoned, and the analogous composts to which they had given rise, 
also quickly fell into discredit.**— p. 635. 

In Oemnaruj, — numerous writers have told us how they under- 



Agricultural Cfiemistrij. 



21 



stand Baron Liebig's doctrine ; we quote from a few of these, 
some of whom have also given their opinion as to the truth of 
that doctrine. 

Professor P. 6. Schulze, of Jena, thus defines Baron Liebig's 
theory (we quote from p. 204 of the ' Patent Office Report ' for 
1848; Washington, 1849) :— 

^The stable manure which agriculluristB furnish, essentially aids Tegetable 
life, only by what it contains of. alkalies, lime, silica, and other mineral ele- 
ments, not by what it contains of carbon, hydrogen, oxygen, and nitr<)gen, 
for these sub^ances plants can obtain from the air, as an inexhaustible source. 
As now in stable manures, the mineral elements bear the proportion of some 
two to seven per cent, of the whole mass, so the agriculturist, who yearly 
brings on hia fields 100,000 cwt. of stable manure, carries out 93,000 to 
08,000 cwt in vain. It would be far more simple and less costly to give 
the plants only mineral manures, and to leave them to acquire their organic 
means of nutriment from the air.'* 

'' In the burning of plants, the organic, not the inorganic portions, are dissi- 
pated. Hence the agriculturist can bum his crops, namely, his straw, and 
yet continue his fields in the strength hitherto possessed, if he only cariies on 
the ashes acquired by such burning. But if circumstances do not permit him 
to manure the plants with such ashes, yet can the same object be attained, if 
hy the aid of chemistry he will examine into the ash constituents of his 
har? eqt, and carry the mifieral substances corresponding to his analysis upon 
his field." 

Dr. Weissenborn, of Weimar, in an article entitled * Observa- 
tions on Liebig's Patent Manure ; with a Comparative View of 
^e Theories of Thaer and Liebig,' thus expresses himself in 
^gard to Baron Liebig's principles : — 

**The great rule of the new system of manuring is the following : — Let the 
fiftldfl not be manured with stable-dung, nor with any sort of dung whatever 
that contains organic (vegetable or animal) substances, along with its inorganic 
(nuneral) principles. This mineral manure the farmer has to procure, either 
by lodnerating all the vegetable substances that he has reaped, and which he 
CMDot profitably sell or consume on his farm, especiallv by burning the straw ; 
^ jv applying to a chemist, with a view of having both the soil to be ma- 
"wed and the ashes of the plant to be cultivated duly analysed, and of getting 
F^P^fed conformably to the result of 8uch analyses an artificial manure 
^?JJ®^ manure, manure of ashes), containing the very mineral food that the 

"TlT*^**' *°^ **"^* ^® °^* already contained in the ground." 
fo/iow ^'^winte^tf* of the new system of manuring are represented to be the 

' • Aiie &nner saves almost the whole of the expenditure for transporting 
2^ y^ ^ the fields, as the weight of the mineral manure he wants is only 

**2 n?^*' °^ ^* ®^ ^^® stable-dung hitherto used, 
riallv » ^^^^ manured afcer the new system, the vegetation cannot mate- 

^iftld straw may be sold; and most of the live stock, that scarcely ever 

u A V^®* revenue, may be dispensed with. 

K, ? rotation of crops is rendered unnecessary, and any sort of crop 
JJj.^ised on the same field without intermipsion. 
. **5^ thetrty of Professor Liebig is refuted by the following principle 
***"*• -ic, Ac—Farmers Magazine, vol. xv. 1847, p. 369. 



22 AgricuUural Chemistry. 

Professor Hugo von Mohl, in his * Principles of the Anatomy 
and Physioloory of the Vegetable Cell,' says : — 

** Instead of reforming agriculture by lus manures, Liebig baa caused tbem 
to demonstrate the incorrectness of his theory qf the nutrition of veffetables,^ — 
English Translation, p. 80. 

Baron Liebig, in his 'Principles,' recently published (p. 
121-123), professes to wonder where Professor Wolff " has found 
what he calls the pwre Mineral Theory ? " Dr. Wolff answers 
him as follows : — 

'' As Baron Liebig does not seem to understand how I became acquainted 
with the so-called ^pure Mineral Theory,^ founded and even yet defended by 
him, I will enlighten him. By the Liebig Mineral Theory every one under- 
stands the idea which was to be practically carried out in the patent manure, 
namely, that when a soil has become exhausted by one or more crops, the 
mineral constituents necessary for the food of plants shall be restored to it in 
sparingly soluble compounds, and in such proportions as a chemical analysia 
of the crop would indicate. By means of the patent manure the same plants 
might be grown iminterruptedly on the same land, and a succession of abun- 
dant crops obtained.'* — 2jeitschr\ft fur Deutsche Landmrthe, 4en Hei't^ p. 112 
(Translated). 

In America — n^nch discussion has taken place regarding Baron 
Liebig's views. Bat, to save space, we will only give one quo- 
tation in connexion with that country. In a letter to Professor 
Webster, Professor E. N. Horsford, whilst with Baron Liebig at 
Giessen, writes, under date May 1, 1846, as follows (we quote 
from the ' Genesee Farmer' of August, 1855) : — 

" You are aware that Boussingaulf has expressed the opinion, after a variety 
of experiments, that the value of manure is in near relatipn to its percentage 
of ammonia. Mulder has, you know, written much in support of the view 
that ulmic and humic acids, ulmates, humates, &c., in one form and another, 

minister largely to vegetation Liebig differs from them all He 

takes the position, that the sources of carbon and nitrogen are carbonic add 
and ammonia in the air 

'' It is obvious (from analyses of soils and rain-water) that the ammonia 
spread on fields in the ordinary distribution of barn-yard products is of no 
moment, THe quantity with usual falls of rain gr^tly eaceeds, in the course 
of a season, any conceivable supply by human instrumentality 

^* But if, in the manure-heap and the liquid accumulations of tbe barn-yard 
transported to the fields, the ammonia be not the chief ingredient, or an tm- 
portant one, to what are we to attribute the unquestioned value of stable pro- 
ducts and nightrsoil P Professor Liebig has shown, that if plants be ma- 
nured with the ashes of plants of the same species, as the grasses of our 
western countnr are wh^n burned over in the fall, they are supplied with 

their natural K)od Let us consider what these ashes are, and 

what manure is. Herbivorous animals derive their nourishment from the 
vegetable kingdom exclusively, their fqod being grass, grain, roots, &c. 
These, with their organic and inor^jpanic matters, are eaten. A portion of 
them is assimilated, becoming hope, muscle, tendon, fat, &c. Another por^ 
tion is voided in the form of excrementitious matter. In process of time the 
bones and tissue follow the same course. What to-day forms the eye, with 
ita sulphur, and its phosphorus, and carbon, &c., will have accomplished 



AgricuUural Chemistry, 28 

its office, and left the or^nism to mingle with the excTements, or escape as 
carbonic acid and water from the lungs. At length all the morgatdc Tnatters 

win le-appear in the voided products The animal orgaoism hhA 

performed the office of a mill. Grain was supplied. Instead of appearing 
as flour and bran, and the intermediate meal, it appears, after intervals of 
peater or less lezigth, in soluble inorganUi talis in the liquid excrements, in 
insoluble inorganic salts in the solid excrements, and in carbonic acid and 
water. Now, after burning a plant, what remains ? It contained, when grow- 
bg, carbon, nitrogen, hydrogen, and oxygen, as organic bodies, and water. 
It contained also, in variable proportions, common salt, potass, soda, magnesia, 
lime, iron, phosphorus, sulphur, and silica. The first. four were expelled in 
the combustion. The remaining ingredients, for the most part, remained un- 
changed. Had the plant gone into the body of an animal, and in the course 
of its evolutions through the oi^anism lost its carbon, hydrogen, nitrogen, and 
oxygen, the remaining incredients would have been the same as before. In 
one case the plant would have been burned in the organism ; in the other, in 
acnicible. The ashes and the excrements are stibstantiallg the same. . . . Nigbt- 
soil and guano are the ashes of animal and vegetable organisms burned in 
iniaial bodies. They are the ashes of plants — the essential food of plants. 
Ilenee their value as manures^ 

So much, then, for the consistency of the interpretations of 
other writers — English, French, German, and American — with 
the interpretations we have ourselves given of the Mineral 
Theory of Baron Liebig. And how, we would ask, are these 
interpretations consistent with those now claimed by Baron 
Liebig and his friends, namely, that " The Mineral Theory " 
" throws upon the air, or upon the ingred^ients of the manure which 
are organic in their. origin, the task of furnishing nitrogen to the 
plants " ? 

Baron Liebig shall answ;er for himself, whether it is upon 
" (he manure " that he throws '* the task of furnishing nitrogen 
to the plant." This one quotation and we have done with these 
lengthy illustrations of Baron Liebig's views. In a letter to the 
Editor of the * Bevue Scientifique et Industrielle,' a translation 
of a part of which is given in the ' Farmer's Magazine,' vol. xvi. 
(1847), p. 511, fipom which we quote, Baron Liebig says : — 

** It has been demonstrated that ammonia is a constituent part of the atmo- 
ipbere, and that as such it is directly accessible and absorbable by all plants. 
Iii then, the other conditions necessary to theg^'owTh of the plants be satisfied — 
if the soil be suitable, if it contmns a sufficient quantity of alkalies, phos- 
J^tetj and sulphates, nothing will be wanting: the plants will derive their 
f'/iMsmafrcm the atmosphere as they do carbonic acid. We know well that 
they are endowed with the faculty of assimilating these two aliments, and I 
really cannot see why we should search for their presence in the manures we 

M? The question of the necessity for ammonia in our manures 

^'swlyes itself into the question of the necessity for animal manures, and upon 
tbe solution depends the entire future prospects of agriculture ; for as soon as 
ve can dispense with bulky farm-yard manure, by the use of artificial prepara- 
tons, the productive power of our fields is placed in our own hands." I 



Thirdly, Having shown what was the " Mineral Theory " ad- 



24 AgricaUaral Chemistry. 

Yocated by Barou Liebig prior to his recently published work, 
and how we and others have understood that theory as bo advo- 
cated, we now pass on to the third main division of our subject ; 
namely, to a consideration of the criticisms of our experi- 
ments and opinions regarding the growth of whsai and turnips ; 
and, in the course of this inquiry, we shall endeavour, by the aid 
of the experiments quoted by Baron Liebig, taken with others 
by their side, to relieve the points which they are calculated to 
elucidate, of the mysteiy and confusion in which Baron Liebig 
has sought to envelop them. 

In regard to our experiments on the growth of wheats Baron 
Liebig says we have drawn the conclusions : — 

1. ** That the mineral constituents of wheat cannot by themselves 
increase the fertility of land,*' 

2. " Thai the produce^ in grain and straw^ is rather proportional 
to the supply of ammonia^ 

We do not object to the definitions here given of our con- 
clusions — subject of course to the amplifications and qiudifica' 
tions which our own papers indicate. But, notwithstanding in a 
public discussion on this subject, we utterly repudiated the 
definition of some of our conclusions assumed by Baron Liebig 
in summing up, and giving his verdict on our opinions at the 
end of his Treatise, he did not scruple to repeat those palpably 
incorrect interpretations of our meaning. 

Let us now see, how it is that Baron Liebig seeks to show, 
that our own experiments contradict the above conclusions, 
Nos. 1 and 2. 

Before we can do this, however, we must first clear the ground 
of a most ingenious objection, by which, as he cannot deny our 
facts, he would seek to throw them aside, as utterly unfit to be the 
foundation for any general conclusions regarding any other land 
than our own, or regarding agricultural practices generally. 

Baron Liebig says, — 

" Mr. La wee has shown, in the most conviocing manner, that in his land 
the mineral constitaents of wheat were present in the f^reatest abundance and 
in an available form ; and no one but Mr. Lawes himself can be surprised 
that, under such circumstances, by manuring with ammoniacal salts only, 
without any addition of mineral matter, he obtiuned during six years a 
higher produce than from the same land unmanured ; for theory plainly pre^ 
diets such a result." — Prirunples, pp 78, 79. 

** Mr. Lawes, then, as appears from these passages, chose for his experiments 
a portion of land which, on account of its neing so rich in available mineral 
constituents, and of its other qualities, was utterly unsuited to his purpose, 
and which ought to have been unhesitatingly rejected, if the object was to test 
the value of the mineral food of plants. And since the mineral manure, in 
these circumstances, could not possibly have the effect expected by Mr. Lawes, 
his conclusions are destitute of all foundation in logic or in facte.*' — p. 60, 60. 

Certainly, this is a very clever way of dismissing the whole of 



r 






AyricuUural Cheinistry, 25 

our experimental evidence : and, in a similar manner, experi- 
ments on ten thousand different soils might be dismissed as ex- 
ceptional, and therefore inapplicable to any other case than the 
particular one in which the result was obtained. In other words, 
the solution of general agricultural questions is not within the 
reach of field investigation ! 

But we propose to show, that these assertions are "desti- 
tute of all foundation in logic or in facts," and that the land in 
question was perfectly adapted to the object in view in the expe- 
riments ; which was, not simply to test the value of the mineral 
food of plants, but to ascertain what was the nature of the 
manure required — mineral or otherwise — ^to restore the produc- 
tive capability for the increased growth of com, which had been 
exhausted by an unusually severe course of cropping on an 
ordinary soil, and which, in the ordinwry course of management, 
would have had its productiveness again increased, by the use 
of the ordinary means of farm-yard manure, fallow, or green 
cropping. 

We must repeat, then, that which we have reiterated so often 
that we are almost ashamed of again troubling our readers with 
the statement, namely, that whatever might be the quality of the 
soil selected (and it was certainly anything but one of the richest 
soils of Great Britain, as described by Baron Liebig), it was 
in a state of practical or agricultural exhaustion, when first sub- 
mitted to experiment. That is to say, it had grown a course 
of turnips, bajley, peas, wheat, and oats, since the application of 
nianure; and it was by this treatment brought into such a con- 
dition of comparative or practical unproductiveness, that no 
fenner paying rent for it, and no landlord letting it, would allow 
It again to grow com without manure In some form. It was, 
moreover, as we have already said, in such a state o{ practical or 
agricultural infertility, that the use of the ordhiary means of 
manure, fallow, or green cropping, would very greatly increase its 
produce. And, whatever may be the opinion or the dictum of 
purely theoretical persons, however high their authority in their 
own department of knowledge, we do not hesitate to maintain 
before the intelligent practical man, that a soil which had been 
submitted to the exhausting treatment above described, and 
wought into the condition here stated, was in a fit and proper 
state for experimenting on with manures, in order to ascertain 
the nature of the corn-exhaustion it had suffered by a course of 
agricultural cropping. 

Bat, in order to prove^ that the soil was in a state of agricultural 
exhaustion, and that it was in a condition to show the efiects both 
cf mineral and organic manures, we have arranged in the fol- 
lowing Table (1.) a condensed summary of nearly the whole of 



I 



26 



Agricultural C/iemistry. 



the results obtained in the field in question, during a period of 
eleven years of the successive growth of wheat. 

Table I. 

Summary, — ^Results of Experiments on the Growth of Wheat. 

Average Total Produce, and Total Increase (Corn and Straw), Iba. per Acre. 



8 



1 

3 
8 

4 
6 
6 



8 
9 

10 { 



General Description of Manures. 



TTnmanored 

Mineral Manure, only . . * 

Farm-yard Manure 

Ammonia-salte, only (Standard Amount) . 
Nitrate of Soda ( = do. do. ) . . . 

Ammonia-salts ( = do. do. ) with Minerals 

Ammonia-salte ) / _ j«, a^ \ a,. a^ 

and Rape^ke [ ( = <^- ^o. ) do. do. 

    » »     ^ — ^^^ ^ -  

Ammonia-salts (less than Standard) do. do. 

Ammonia-salts (more do. do. ) do. do. 

^^B^pe-CjSe } < ^®- ^^- ^®- > ^®- ^^' 



t 




Total 


Total 


Number 


Numbei 


Prodace 


Increaae 


of 


of 


(Corn 


(Com 


Years. 


CSases. 


and 


and 






Straw). 


Straw). 






Iba. 


lbs. 


11 


27 


3864 


• • 


8 


40 


8018 


154 


11 


11 


5036 


3173 


9 


86 


4857 


1993 


8 


4 


4907 


3043 ' 


9 


117 


5531 


3667 


6 


13 


5540 


3676 


6 


17 


4536 


1671 


8 


81 


6445 


3581 


6 


83 


6016 


3153 



The plan of this Table (I.) is as follows. We have taken the 
average total produce per acre (com and straw) of all the plots in 
each separate year which were unmanured, and then the average 
of these for the eleven years of the experiment : the number of 
cases in all, as seen by the Table, amounting to 27. In like 
manner the average is taken of all the cases in each year in which 
mineral manures alone were employed, and then the average of 
these results of the individual years, by dividing their sura by the 
number of years ; and so on, with the cases where farm-yard 
manure, ammoniacal salts, or any of the other characteristic con- 
stituents or combinations, as indicated in the Table, were em- 
ployed. The last column in the Table — that of total increase — 
represents the average annual total increase in lbs. (that is, com 
and straw together), obtained from the manured over that of the 
unmanured plots. 

We are not, it is true, favoured with any numerical statement 
whatever, either summary or in detail, of the experiments on the 
" Liebig's Height " ; but we should not ourselves have thought 
of asking confidence in such a mere condensed summary as we 
now give, were it not that many of the results which go to form 
it, are already before the readers of this Journal, and the remainder 
we trust will be so in the course of time. This being so, we do 
not doubt that this summary will be accepted as both much more 
convenient, and better adapted for the discussion of the more 
prominent and characteristic facts, than a series of elaborate 



^ Agricultural Chemutry. 27 

tables of detail. Leaving, then, entirely out of the question, on 
this occ^ion, all detail or discussion as to the amount and 
specific description of the different manures, and also as to the 
varying proportions of corn and straw respectively, which make 
up the sum of the total produce, according to season, the manures 
employed, &c., let us see what are the broad and main features 
brought out by this immense mass of experimental evidence. 

The average annual total produce (com and straw) per acre 
unmanvredj including the results of eleven years, and extending in 
all to 27 cases, is 2864 lbs. The average annual increase over this 
amount, obtained by various purely mineral manures^ in 40 cases, 
distributed over eight different years, is only 1 54 lbs. The increase 
hj farm-yard manure on the other hand, taking the average of 
eleven years, is 2172 lbs. It is clear, therefore, that there are 
here 2000 lbs. of increased produce, beyond that which the 
mineral manures were adequate to yield. Again, it is seen (in 
Series 4), that the average of 36 cases of purely ammoniacal 
manure^ ^ve an average increase over the unmanured plots of 
1993 lbs. ; whilst nitrate of soda, another manufe whose efficacy 
is dae to the nitrogen it supplies, and which was applied in 
quantity as nearly as possible equal in nitrogen to that of the 
ammonia-salts, has given a mean average increase of 2043 lbs. 

In the next series (6), we have 117 cases, distributed over nine 
years, in which ammonia-salts, were employed, in quantity equal 
in their contents of nitrogen to the ammonia-saltis of Series 4, 
and the nitrate of soda of Series 5 ; but we have here (in Series 6), 
the addition to the nitrogenous manure of various purely mineral 
manures ; and the increase then rises to 2667 lbs. instead of only 
about 2000 lbs. with nitrogenous manure alone ; so that, with 
this combined mineral and nitrogenous manure, the produce 
considerably exceeds that by farm-yard manure. Whilst, then, 
an excessive supply of nitrogenous manure alone has produced 
an average increase of about 2000 lbs., the further addition of 
minerals has, when there was at the same time a large amount 
of nitrogen artificially provided vdthin the soil^ given a further 
average increase of 674 lbs. ; though, when these minerals were 
^ed without an excess of nitrogen in the soil, the average 
increase they yielded was only 154 lbs. 

It is Been then, that mineral manures alone, increased the pro- ] 

duce of this agriculturally exhausted field in no practical degree ; 
that pure nitrogenous manures increased it nearly as much as I 

the ordinary manure of the farm ; and that nitrogen together with | 

mmerals gave a produce nearly double that of the unmanured t 

land,and considerably exceeded that by farm-yard manure. ^'That , 

'A« mineral consHMients of wheat cannot by themselves increase the i 

f^iiHy of land " — and " that the produce in grain and straw is 



28 Agricultural Clcemistry, 

rather proportional to the supply of ammonia '* — would be con- 
clusions from these simple facts, far more logical than many 
which we are expected to receive without any facts at all. 

To proceed. May it not be said that the effect of the farm- 
yard manure upon the increased growth of wheat, was due 
in some way or other to its carbonaceous substance, rather than 
chiefly to its nitrogen, and to a small extent to its minerals in 
connexion with that nitrogen ? This supposition is negatived 
by a comparison of the results of Series 7 with those already 
discussed, which throws some light upon the relative effects of 
the nitrogenous, the carbonaceous, and the mineral constituents 
of manure, upon the increased growth of wheat, on a corn- 
exhausted soil. Series 7 gives the average of 12 cases, distri- 
buted over six years, in which rape-cake, either with or without 
ammonia-salts, was employed in such quantity as to provide 
nitrogen exactly equal to the ammonia-salts of Series 6 ; and as 
in the latter, so also in Series 7, minerals were always added. 
We have here the striking result, of an average difference of 
produce of only 9 lbs. between Series 6 and Series 7, there 
being in the two cases an identity in amount of nitrogenous 
supply ; and this, notwithstanding that the rape-cake employed 
in Series 7 would itself supply a considerable amount of addi- 
tional minerals, and also a large quantity of ctkrbonaceous 
substance, neither of which have given an appreciable increase 
beyond that of the equivalent nitrogen and minerals of Series 6. 

In Series 8 we have, together with the minerals, less ammonia- 
salts than in Series 6 ; and with this less amount of ammonia or 
nitrogen, we have only 1671 lbs. of increased produce, instead of 
2667 lbs. as in Series 6. In Series 9, on the other hand, we have 
with the minerals, more ammonia than in Series 6, and with this, 
a considerably increased amount of produce also ; that is to say, 
when with the minerals we have applied a larger amount of am- 
monia in the manure than the " standard," we have an average 
annual increase of total produce per acre of 3581 lbs. ; with only 
the *' standard " amount of ammonia, an increase of 2667 lbs. ; 
and with less ammonia than "standard," an increase of only 
1671 lbs. And, finally, in Series 10, with minerals, rape-cake, 
and ammonia, containing together more nitrogen than in Series 6 
and 7, we have, taking an average of 22 cases, and extending 
over a period of five years, an average increase of 3152 lbs.; 
instead of 2667 lbs. and 2676 lbs. in Series 6 and 7 respectively. 

Surely in the results of this comprehensive summary of experi- 
mental evidence, we have good grounds for concluding, that this 
practically corn-exhausted field was in a condition to test the 
nature of that exhaustion, and of the constituents requisite to 
restore it to that condition of practical com productiveness, 



Agricultural Chemistry, 29 

which the ordinary means, of farm-yard manure, fallow, or green 
cropping would attain ; and, if it be really so, there surely has 
been some light thrown upon the important question of the 
source of the efficacy of these well-recognised practices, so far 
as the growth of grain is concerned. 

The object of this inquiry really was, then, to determine by 
what constituentfl of manure the produce could be raised from the 
normal amount of its agriculturally exhausted state — no matter 
whether this was 17 bushels or — up to the point of which it 
was capable by the ordinary means of intelligent and successful 
farming. This is the practical question, the question for agn- 
cuUure, And we repeat, that, inasmuch as by the means that 
were employed we obtained an increase per acre of 10 to 15 
bushels or more, with its equivalent of straw, over the produce 
of the nnmanured land, whateijer this last might he — we say that, 
as this was the case, our soil was in a fit and proper state to 
elucidate the important agricultural question as to what was the 
nature of the exhaustion suffered by a course of agricaltaral 
cropping, and as to what constituents it was necessary to provide 
before the produce of grain could again be raised, from that of 
the practically exhausted, to that of the practically fertile condi- 
tion of the land. 

* 

But Baron Liebig has said that, because we obtained an average 
produce of 1125 lbs. of grain and 1756 lbs. of straw, during 
seven consecutive years, that this was a sufficient proof — 

''that the soil was naturally so rich in available mineral constituents, of the 
kinds required by plants, that manuring with 4 cwt. of mineral manure per 
•ere, a quantity which, spread over the ground and mixed with the soil 
to the depth of 12 inches, gives 1 grain to 20 cubic inches of soil, could most 
certainly (troduce no effect, or, at the utmost, a very trifling one. For, in 
the first y ear, the soil contained seven times, or about 85 per cent, more of 
these subatances than was required for one crop." — VrindpleSf p. 68. 

Now, if it really were so, that our *' soil was naturally so rich in 
available mineral constituents of the kinds required by plants," 
w BaroiD Liebig admits, is it not the strongest condemnation 
vrVich could possibly be conceived of the doctrine presented in so 
many forms to the farmer, namely, that " if only the soil contain 
a sufficient supply of the mineral food of plants," then " the 
ammonia required for their development .will be furnished by 
"le atmosphere"? Is it not, we ask, the strongest possible 
condemuation of such a view that, with the soil in this supposed 
iiaturally rich condition, the produce should still be less, by 
'^^^Y bushels of corn, and their equivalent of straw, than that 
obtained on the simple addition of available nitrogen to the soil ? 
^^^^ when Baron Liebig tiow informs us that — 

no one but Mr. Lawes himself can be surprised that, under such circum- 
^^uices, by manuring with ammoniacal salts only, without any addition of 



30 Agricultural Cliemisiry, 

mineral matter, he obtained during six jears a higher produce than Aram the 
same land unmanared ; for theory plainly predicU such a result ^ — Principles^ 
p.78— 

we ask, is not this again the condemnation by Baron Liebig 
himself of his own jpreviously insisted-upon doctrines, as already 
shown in quotations from his works, and in other words in his 
letter to the -editor of the * Bevue Sci&rUifique et IndusirieUe^ 
namely, that — 

'' if the soil be suitable, if it contains a sufficient quantity of alkaKes^ pAoS'. 
phateSf and sulphates, nothing will be wanting ; the plants will derive their 
ammonia from the atmosphere, as they do carbonic acid " ? (1) 

Again — with regard to the assertion, that the amount of 
mineral manure supplied in our experiments was so small in 
proportion to the whole bulk of soil, that it " could most cer- 
tainly produce no effect,, or, at the utmost, a very trifling one," 
we may answer — 

1st, That mineral manures, applied to a similar description of 
soil, and in no greater proportion to its total bulk, haye most 
marked effects upon the growth of turnips and our leguminous 
crops, 

2ndly, That the €ame mineral manures, applied in the same 
proportion to the bulk of soil, have a distinct effect, even upon 
the cereals^ when there is an almndance of availahle nitrogen pro^ 
vided vnthin the soil itself, 

Srdly , That salts of ammonia, and other compounds of nitrogen^ 
applied in even less proportion to the bulk of soil, increase the 
produce of wheat in the particular 'soil in question, from that of 
agricultural exhaustion to that of high agricultural productiveness. 

Let us now see by what kind of reasoning Baron Liebig 
believes that he can " convey to the reader the full conviction " 
that our own experiments not only contradict the conclusions 
*nhat the mineral constituents of wheat cannot by themselves 
increase the fertility of land," and " that the produce in grain 
and straw is rather proportional to the supply of ammonia," bat 
that they are also the " strictest and most satisfactory proofs " of 
his own opinions. 

Those of our results which he particularly brings under 
criticism with this view, are — 

1st, Those of the continuously unmanured plot; and, 

2ndly, Those of a plot (10a) which, after having had mineral 
manures in the first year, without yielding any practical increase 
of produce, had then ammonia salts only, for a series of years ; 
by means of which, a large number of heavy crops have been 
obtained. 

In Diagram I. (annexed) we have the results of these two plots, 
and those also of plot 106 by their side, from the commencement 



ff *U4 /«¥( J/ 



Plots I 1844 I 1845 i 1846  184^^55 



Ejgjlaii 




r 



Agricultural Chemistry, 31 

of the experiment up to the present time — that is to say, from 
1844 to 1855 inclusive. And, as before, we give in this place 
as little detail as possible, in order that the main and more 
general facts may stand out the more prominently. 
The plan of the diagram is as follows :— 
In the top line of figures are stated the years during which 
the experiments were conducted. In the second line of figures 
tike total produce (com and straw) per acre per annum of Plot 3 ; 
the continuously unmanured plot. 

In the third line of figures, we have the produce of Plot 10a ; 
which was manured in the first year with a mineral mixture, 
containing superphosphate of lime and silicate of potass, and in 
every succeeding year, with a somewhat excessive amount of 
ammonia salts only. 

In the fourth line of figures is given the total produce of Plot 
106 ; which in the first year had ^e same minerals as Plot 10a, 
and afterwards, sometimes the same amount of ammonia salts as 
the latter, sometimes no manure at all, sometimes a complete 
mineral manure in addition to the ammonia salts, and some- 
times the mineral manure alone. 

And, in the two lower lines of the diagram, we have the 
increase of total produce over that of the unmanured plot, on the 
Plots 10a and lOZ/ respectively. 

And in order that the comparison, both as to the general 
character of the manuring, and the amount of produce, on the 
several plots, may be brought to one convenient view, the state- 
ment of the manuring is not repeated ; but only indicated by 
squares of colour, which may be supposed to represent the 
different plots, thus : — 

Unmanured — uncoloured. 
Mineral manure — blue. 
Ammonia salts — yellow. 
Minerals and ammonia salts together — green. 
Before entering upon a comparison of the results of the several 
plots, we must pass under review Baron Liebig's remarks on the 
produce of the unmanured plot ; by which he not only seeks to 
show, that our soil was naturally so rich in available mineral con- 
stituents, as to be utterly unfit for experiment — an objection of 
which we have already disposed — but he also seeks to draw the 
conclusion from the variable amount of produce of the unma- 
nured plot in different years, that this was due to the variable 
amount of mineral constituents dissolved in the soil in the same 
time ; and hence, he seeks to claim the greater accumulation by 
the plant, in one year than in another, of carbon and nitrogen 
from atmospheric sources, simply as the result of an increased 
supply to the plant of soluble or available minerals. 



32 Agricvltural Chemistry. 

Thus, comparing the produce of 1844 with that of 1845, thfe 
latter being twice as great as the former, he says : — 

^ If in the year 1844 a certain amount of rain fell on the land, and thuB a 
certain amount of mineral constituents was rendered available for the plant ; 
and if, in 1845, there fell, at the favourable season, one balf more rain, this 
obviously dissolved one-half more of mineral constituents. Had these not 
been dissolved they could not have entered the plant and been there eisployed 
— that is to say, without their aid the crop of 1845 could not have increaiaed 
by one-halt 

** That to which, in these remarks, I wish particularly to direct the attention 
of farmers, is the fact that, in this striking case, the produce of the land in 
grain and straw, and therefore in nitrogeniaed matters, was much increaaed 
without the smallest addition of nitrogenous manure, for the land received 
no manure whatever; and solely from the increase in the amount of the mineral 
constituents, present in the soil, dissolved in the same time,^ — Principles^ pp. 
69,70. 

Here Baron Liebig maintains that the larger amount of mine- 
rals dissolved by the increased fall of rain enabled the plant to 
appropriate the additional supply of nitrogen from atmospheric 
sources. We hold, on the contrary, that, owing to climatic 
variations, the atTnospheric supply, either through the medium 
of the. soil, or directly to the plants themselves, or both, was 
greater ; therefore the plants were enabled to take up a larger 
amount of minerals from the soil. And that this was so, is, we 
think, susceptible of proof far more logical than the contrary 
supposition. Thus our experiments show — 

1st. That the varying produce of the unraanured plot by no 
means bore any constant and direct relation to the varying amount 
of rain-fall of the different seasons ; that is to say, to the amount 
of mineral solvent ; but that, on the contrary, it depended much 
more on the coincidence with a certain amount of rain-fall, of 
those conditions of atmosphere as to temperature and moisture, 
which Baron Liebig himself admits must influence the amount 
of fluid passing through the plant, and which are also known to 
imply a greater power in growing plants to assimilate atmo- 
spheric food — even though it cannot be supposed that they effect 
a greater solubility of the minerals. Whilst, without this greater 
available supply of atmospheric nutriment, either to the roots or 
to the leaves, the necessary and abundant mineral constituents 
in the soil would have been utterly unavailing. 

2ndly. That a direct svpply of soluble mineral constituents 
yielded scarcely any increase over the unmanured plot ; whilst 
the supply of available nitrogen — even with one and the same 
set of conditions as to mineral supply, rain-fall, and temperaiure, 
nearly doubled the amount of produce. That is to say, an 
. increased supply of the normally atmospheric food of plants 
had a far greater effect in enabling the plants to take up 



Agricultural Chemistry. 33 

from the soil and assimilate an increased amount of their 
necessary mineral constituents, than either the direct supply of 
the soluble minerals, or an increased amount of rain or mineral 
solvent. 

The varying produce of the unmanured plot was therefore, not 
in proportion to the amount of soluble or available soU-^opet* 
cmstitueifUs — that is, minerals — which, even when existing in ex- 
0^8, were utterly powerless, unless, either by climatic variations 
or by direct nitrogenous manures, additional supplies of the uor- 
mally atmospheric food of plants were at the same time provided. 
True, no one will doubt the assertion, that ^^ had these consti- 
tuents not been present in the soil, an increased supply of carbonic 
acid and ammonia from the air could not have had any effect on 
the crop." Such an assertion, thanks to Baron Liebig, is at the 
present day a simple truism. And, we must here again remind 
the unwary reader, that the question between Baron Liebig and 
ourselves, has never been, whether or not plants could grow 
without a due supply of mineral constituents, but, as we have 
amply shown by the copious quotations given in the earlier part 
of this paper, Baron Liebig's doctrine has been — and indeed 
many passages in his new work would indicate that it still is — 
that " if only the soil contain a sufficient supply of the mineral 
food of plants," then " the ammonia required for their develop- 
ment will be famished by the atmosphere " ; or, as he now has it, 
when spefJ^ing of the varying produce of our unmanured plot, 
" a larger quantity of these mineral substances became active in 
the same time, and the surface of the land w^as thus enabled, hy 
the plants grovnng on it, to absorb from the air one-half more car- 
bonic acid and ammonia than in the preceding year." We, on 
the other hand, maintain, not that the mineral constituents can be 
dispensed with, but that in the ordinary course of agriculture with 
rotation, they exist relatively to other constituents in abundance, 
and that, notwithstanding this abundance, the main saleable pro- 
duce of the farm, the cereal grains, are utterly incompetent to 
yield a full agricultural crop, unless there be artificially provided, 
irithin the soil itself a liberal supply of available nitrogen, nor- 
mally the atmospheric food of plants. The question, then, is, 
not whether mineral constituents are essential to the growth of 
plants, nor whether the supply of them in manure will yield an in- 
crease of grain />ro?'ifod flwre he an excess of availalth nitrogen vithiib 
ike «oiJ— for both of these postulates we need not say we fully 
assent to — but it is and has been, whether or not a liberal supply, 
of the soluble mineral constituents of the cereals, to a soil suffering 
^he exhaustion of an ordinary course of rotation, will enable 
the crop to assimilate in any practical and agriculturally adequate 
^^gree, a larger amount of nitrogen from atmospheric sources ? 

C 



34 Agricultural Cliemistiy. 

To this we answer in the negative. And, let us see, how Baron 

Liebig seeks to show that oui* experiments oontradict the 

equivalent assertions — '^that the mineral constituents of wheat 

cannot by tliemselves increase the fertility of land," and ^' that 

the produce in grain and straw is rather proportional to the 

supply of ammonia." 

We have before explained (see Diagram I.), that plot 10 

of our experimental wheat-field was manured in 1844 with a 

mixture of silicate of potass and superphosphate of lime, and in 

every subsequent year one portion of it (10a) received a very 

liberal amount of ammonia salts only : the result being a very 

considerable increase of produce compared with the unmanur^ 

plot. This increase, according to Baron Liebig, is due to 

the— 

'* conRtituenU of the soil, plus 660 lbs. of superphosphate of lime, plus 220 
lbs. of soluble silicate of potasa, plus 1960 lbs. of ammoniacal salts ; " 

And he goes on to say — 

'' it follows that the increase of produce was by no means the effect of tlie 
ammonia alone, as Mr. Lawes will have it, but that the active mineral con- 
stituents of the soil just mentioned have had their lull share in producing 
this effect. 

<< What, then, are the circumstances in which theory leads us to anticipate 
such an increase of produce P 

'' The answer will be found in my work, p. 134.'' 

We give the sentence as it really does cjccur at page 134 of 
the fourth edition of Baron Liebig's work, the portions between 
brackets, thus [ ], being omitted by Baron Liebig in his quo- 
tation (Principles^ p. 109) : — 

" The cereals require the alkalies and silicates liberated by the lime, and 
rendered fit for assimilation by plants. If there be present decaying matter 
yielding to tlie plants carbonic acid, their development may be mvoorad bj 
this means; but this is not necessary. For if we nimish to the soil ammonia, 
and to the cereals the phosphates essential to their growth [m the event af 
their being deficiently we famish all the conditions necessary for a rich crop 
[as the atmosphere jorms an inexhaustible moffosdne qfcarbcnie add]," 

Now, the object of this sentence in Baron Liebig's work was 
simply to explain that the beneficial action of burnt lime upon 
soils depended upon its liberating in the soil, the *' alkalies arid 
siiiccUes '' which the cereals require, and that, as the amount of 
humus must thereby be lessened, it was obvious that, in the 
event of other constituents not being defideni, the plants were 
enabled to rely upon the aimo&phere as an inexhattstible majgaaine 
of carbonic adi. Whether or not Baron Liebig's " Theory," as 
amply developed in entire chapters of the same work, as well as 
in other writings, is properly represented by this individual and 
mutilated sentence, the reader will judge for himself, from the 
evidence we have adduced as to what that theory really was. 



Agricultural Chemistnj. 35 

But can the increase of prodace of plot 10a over the unraanured 
plot be attributed to the efficacy of the mineral constituents 
BappUed in the first year, in the sense in which Baron Liebig 
attributes efficacy to soluble mineral manures ; namely, as in- 
creasing the assimilation of nitrogen from atmospheric sources ? 

Diagram I. shows that the minerals alone (superphosphate of 
lime and silicate of potass), which were employed in 1844, gave 
only 77 lbs. more produce than the unmanured plot. 

In 1845, a liberal supply of ammonia salts alone, to this plot 
10, on which soluble minerals alone had given scarcely any 
increase in the previous year, increased the produce over that of 
the unmanured plot by more than 2000 lbs. 

In the third year (1846), this plot 10 was divided into two 
equal portions. One-half (10a) again received ammonia salts 
alone, and the other (10&) no manure at all. 

Now surely, if the soluble minerals supplied in the first year, 
are to have so much of the credit of the increase of crop during 
the seven years, and if, with " a sufficient supply of the mineral 
food of plants,*' ..." the ammonia required for their develop- 
ment will be furnished by the atmosphere," surely, upon these sup- 
positions, we ought to get some increase of produce over the con- 
tmuonsly unmanured plot, on plot lOfc, in this third year (1846) ; 
when, having had, but two years previously, this supposed very 
efficient supply of minerals, it is now left unmanured. The fact 
is, however, that in 1846 the continiumsly unmanured plot gave 
2720 lbs. of total produce, and plot lOfc only 2671 lbs. !— though 
10a, where ammonia salts were again applied, gave 4094 lbs. ! 
The result is, then, that plot 106, with minerals in 1844^ ammonia 
in 1845, and no manure at all in 1846, gave even rather less 
prodace than plot 3 (the continuously unmanured plot), which had 
had no supply of minerals at all. How, we would ask, are these 
facts consistent with attributing the increased produce during the 
seven years on plot 10a " to the one only constant value which ope- 
rated " in the experiments — " that is, to the total sum of the avail- 
Me or soluble nutritive mineral constituents present in the 
Boil " ? The obvious truth is, that however liberal the supply of 
minerals in the soil, they were utterly incompetent to yield 
any agriculturally adequate increase of produce of wheat, unless 
accompanied by an artificial supply of available nitrogen within 
the soil ; and this being so, we would ask — Was not the produce 
" rather proportional to the supply of ammonia " ? 

In 1847, plots 10a and 106 both received equal amounts of 
ammonia-salts alone, and gave nearly identical amounts of pro- 
dace, and half as much again as the unmanured plot. 

In 1848, the produce of the unmanured plot was 2664 lbs. ; 
that of 10a, with ammonia salts only, for the fourth vear, 

c 2 



86 AgricuUurcd CJiemistry, 

3701 lbs. ; but 106, with minerals and ammonia, gave 4530 lbs. 
Kere, then — after growing wheat successively year after year hy 
means of very la/rge amounts of a/m/inoniar^aMs, upon land pre- 
viously exhausted hy a heavy course of cropping — we find a distinct 
effect from the admixture of minerals with a further dressing of 
ammonia. But is this action of minerals in rendering efficient 
an excessive supply of ammonia in the soil, after such a course of 
mineral exhaustion as never happens in the ordinary coarse of 
farming with rotation — is this the action still insisted upon by 
Baron Liebig, namely, that of enabling the surface of the land, 
" by the plants groumig on i/, to absorb from the air " a larger 
amount of carbonic acid and ammonia ? 

In 1849, both plots (10a and 10&) were again supplied with 
equal quantities of ammonia-salts alone, and both gave more than 
2000 lbs. increase over the unmanured plot ; whilst 106, with its 
liberal supply of minerals the year before, only gave 125 lbs. 
more than 10a. 

In 1850, ammonia salts alone on 10a again gave more than 
2000 lbs. of increase ; but 106, to which minerals were added 
— this time udthout ammonia — gave only 399 lbs. of additional 
produce, this slight amount being chiefly due to a small residue 
of ammonia remaining in the soil from the high ammoniacal 
manuring of the previous years. 

That the minerals employed in 106, though yielding only 
399 lbs. of increase, still practically exhausted the soil of its im^ 
mediately available supplied ammonia is obvious from the resnlta 
of the next two years (1851-2). Thus, witli a large and equal 
supply of ammonia-salts only to both plots (10a and 106) in these 
two years, we have almost identically the same amount of produce 
on the former as on the latter; although 106 had not only 
twice received a liberal supply of minerals, which had been 
withheld from 10a, but had also given a less gross total produce, 
reckoning from the commencement of the experiment. 

From this time — although the continued application of am- 
monia-salts only on 10a, gave in the ninth year an increase of 
919 lbs. ; in the tenth, of 2312 lbs. ; and in the eleventh, of 
937 lbs. of corn and straw — the employment on 106 of minerals, 
in addition to the excessive amount of ammonia, produced a still 
further increase. 

What, then, is the general result of these experiments? 
Excluding the first year, in which the plots 10a and 106 both 
received mineral manure without yielding any practical amount 
of increase, it is as follows : — On the average of eleven years of 
the continuous growth of wheat, the unmanured plot gave a totid 
annual produce (com and straw) of 2856 lbs. ; plot 10a, with 
eleven years of ammonia salts alone, gave 4534 lbs., being 



Agricultural Chemistry, 37 

an increase over the unmanured plot of 1678 lbs. ; and plot lOft, 
with nine years of ammonia salts and two years of minerals, 
gave an annual average of 4642 lbs. of total produce, and of 
1786 lbs. otiTicrease. That is to say, plot lOh has only given 
during these eleven years, an annual increase of 108 lbs. more 
total produce than plot 10a, although during this period it re- 
ceived considerably more than ten times as much of all the 
more important mineral constituents, except silica, as would be 
contained in the total increase in the eleven years, of 10b over 
10a ! In fact, all that this mineral supply has done, has been 
to render efficient that amount of amim^onia, which was added 
in excess of the annually available supply of minerals &om the 
soil itself. 

But in Diagram II. (p. 31), we have even a more striking 
answer still, to the assertion that in our experiments the whole 
produce is proportional " to the total sum of the available or 
sdvbls nutritive mineral constituents present in the soiV The pro- 
dace of two plots (17 and 18) is here compared with that of the 
continuously unmanured plot. The results extend over a period 
of six years, namely, 1850 to 1855 inclusive. As before, the 
unmanured space is uncohured ; mineral manures are represented 
by blue ; ammoniar-saUs only by yellow ; and the mixture of both 
imnerals and ammonia by green. 

It should be mentioned, that the plots (17 and 18) had, pre- 
viously to 1850, been manured somewhat similarly since the 
commencement of the experiment in 1844. They had generally 
received a liberal supply of minerals and of nitrogenous matter 
also; plot 17 having had upon the whole rather more nitrogen 
supplied to it than plot 18. 

In 1850, both plots (17 and 18) received a large amount both 
of soluble minerals and of ammonia-salts, and they each gave 
nearly a ton and a half more produce than the unmanured plot ; 
though plot 17, which had been rather the most highly manured 
thoughout the previous years, gave rather more produce than 
plot 18. 

In 1851, plot 17 received the same amount of minerals and 
ammonia as previously, and gave 2905 lbs. of increased produce. 
Plot 18 received no minerals, but the same amount of ammonia 
as plot 17, and the result is nearly as much increase, that is, 
2864 lbs. instead of 2905 lbs. 

In 1852, plot 17, which had minerals and ammonia the ye?ir 
tefore, has now only ammonia ; and plot 18, which had am* 
monia only in the previous year, has now only minerals. The 
Tesult is, that the ammonia plot (17) gives 5418 lbs. of produce, 
or 2691 lbs. of increase ; whilst the mineral plot (18) gives only 
2620 lbs. total produce = only 163 lbs. increase. 



88 AgiicuUural Chemistry. 

In 1853, the plot which had previously ammonia only, has now 
only minerals ; and the one which had minerals only, has now 
only ammonia. And we have again with the ammonia 4773 lbs. 
of produces 3001 lbs. increase; and with the minerals only 
2533 lbs. of produce as 761 lbs. of increase. 

In 1854, the manures are again transposed ; and this being 
a very favourable season, we have, with the ammonia, 7923 lbs. 
of produce =442 7 lbs. of increase, or nearly 2 tons; and with 
the minerals ouly, 3915 lbs. of produces=419 lbs. of increase, 
or more than 4000 lbs, per acre less increase than with the a/mmonia 
salts. 

Lastly, in 1855, the manures being again transposed, so also 
is the relation of produce on the two plots — ^the ammonia plot 
giving 6265 lbs. of produce =3405 lbs. of increase; and the 
mineral plot only 3059 lbs. of produce=199 lbs. of increase. 

Tracing the history" of each plot separately, the iificrease over 
the unm>anured plot is as follows: — Plot 17, with minerals and 
ammonia, in 1850, 3332 lbs. ; with the same in 1851, 2905 lbs. ; 
with ammonia only in 1852, 2691 lbs. ; with minerals only in 
1853, 761 lbs. ; with ammonia only in 1854, 4427 lbs. ; and with 
minerals only in 1855, 199 lbs. of increase. Plot 18 again, with 
minerals and ammonia in the first year, gives 3054 lbs. ; with 
ammonia only in the second year, 2864 lbs. ; with minerals 
only in the third year, 163 lbs. ; with ammonia only in the 
fourth year, 3001 lbs. ; with minerals only in the fifth year^ 
419 lbs. ; and with ammonia only in the sixth year, 3405 lbs. 
of increase, in each case, over the unmanured plot. 

We ask then, do these results either contradict the assertions, 
*' that the mineral constituents of wheat cannot hy themselves 
increase the fertility of land/' and *' that the produce, in grain 
and straw, is rather proportional to the supply of ammonia " ? — or 
do they ^* prove*' what we *' intended to dtisprovey" namely, that 
the whole produce is pi'oportional '' to the total sum of the 
avaUahle or soluble nutritive mineral constUv£frds present in the 
soU " ? 

What the *^ Mineral Theory " of Baron Liebig, as developed 
in his previous writings, really . was — how that theory was 
understood by others as well as ourselves — and how inde- 
pendent, according to it, our cultivated plants should be of 
available nitrogen supplied to the soil, if only they are liberally 
provided with their necessary mineral constituents — the reader 
is by this time fully aware. He has also seen, that in 
passages and arguments in Baron Liebig's recently published 
" Principles^'' this identical ** Mineral Theory " is still main- 
tained ; and also, how strenuously he has endeavoured to show, 
that the increase of produce in our experiments was due, not to 



Agrictdtm'al Chemistry, 39 

the efficacy of the ammoniacal ealts employed, but '' to the total 
sum of the available or soluble nutritive mineral constituents 
present in the soil." Bvi now for the other side of the question ! 

Besides stating, as already pointed out — and in spite of his 
lengthened argument and summing up to the contrary — ^that the 
increase we obtained by manuring with ammoniacal salts alone, 
was only what theory plainly predicted, he says — 

*' When we remember that it is the object of scientific research to discover 
&e cause of tbe efficacy of ammoniacal salts, we must not forget, in our in- 
qairieft, that the increase ofprodtice, obtained by the use of these salts, is to be 
regarded m itself as a firmly established fact, which can in no way be afiected 
by the views we may entertain as to its cause." — Principles, p. 98. 

The efficacy of ammoniacal salts in yielding an increase of 
produce, not only in our own experiments, but as a "^rmZy- 
edablished fact" is now then fully admitted. And as it was 
impossible, in the face not only of our own particular experi- 
ments, but of now generally recorded experience, to avoid this 
admission in some form, how is it that Baron Liebig brings this 
result into consistency with the theory which supposes the 
increase to be proportional to the soluble minerals present 
in the soil ? We could blush for Baron Liebig as we quote his 
words : — 

''In these experiments, three portions of land were each manured, for 
leven years, with mineral manure (mineral constituents of the soil and 
ammomaeal salts) " 

And again, in the same page — 

Mt follows from this, that /arm-^n/ or stable manure can be replaced in 
iti entire effect by mineral manure; and not only replaced, for it can be, by 
the use oimineral substances alone {sulphate of ammo>nia and sal-ammoniac 
are mineral), surpassed in its fullest efficacy." — Primaries, p. 90. 

Thus then ^' ammoniacal-ealts," " sulphate of ammonia, and 
sal-ammoniac," are to be classed as mineral manures ! This is in- 
dsed begging the whole question ! But a mancBuvre so transparent 
as this, would not even require notice, were it only addressed to 
the scientific reader. As it is, however, it is necessary to remind 
t^e uninitiated or unwary, that throughout the discussions on 
the subject of agricultural chemisty during the last ten or a 
dozen years, the term " miTieral manure " has acquired an entirely 
technical significance, and that it has been employed to designate 
those constituents which, when assimilated by the plant, would 
remain as ash after its incineration ; and it has been used, empha- 
tically to distinguish such constituents of plants or manures, from 
the combustible or volatile portions — ^that is, from the nitrogenous 
or ammoniacal, the carbonaceous, &c. Indeed, we need not go 
&r to establish, from the words of Baron Liebig himself, the 



40 Agricultural GJiemistry. 

recognisecl distinction^ in ctgriaidtural discnssions, between the 
terms mineral^ and ammoma or am-iMmiobcal. Thus he says : — 

** The mineral confluents act, as is shown by the nroduce of the un- 
manured land, without any artificial supply of ammonia. 

^ The ammonia incieasea the produce only if the minerid constitueats he 
pretient in the soil in due quantity and in an availahle form." 

*' Ammonia is v/ithout enect if the minercU constituents are wanting. Con- 
sequently, the action of ammonia is limited to the acceleration of the action 
of the mineral constituents in a given time." — Principles, pp. 86, 87. 

** . . . The other is the action of sulphate of ammonta as a aolvent for 
certain important mineral constituents of the soil.'* — lb. p. 9ih 

** Ammonia, when used as a manure alone, and when there is a want of 
mineral constituents in the soil, is like the B])irits which the labourer takes, in 
order to increase his available labour, power, or imagioation.'" — /6« p. 106. 

It is needless to multiply quotations. The ruse has not, how- 
ever, been entirely without success. For in public discussion 
of the subject at the late Meeting of the British Association, 
before Baron Liebig himself, one of his advocates stated, that 
the difference between Baron Liebig and ourselves rest^ mainly 
on a misunderstanding — on a different use of nomenclature — for 
" salts of ammonia are mineral manures " .' This method of 
begging the whole question was, however, we were glad to find, 
entirely disallowed by mutual friends of Baron Liebig and our- 
selves with whom we conversed on the subject ; and we are 
glad to find, that writers of the agricultural press have also 
expressed their sense of this manoeuvre. ThuQ, in an able 
article on this discussion in the " North British Agriculturist " 
(Nov. 7, 1855), the writer says — ''Neither can we think him 
justified in claiming sulphaie of ammonia and saUa/mmonia/i as 
mineral substances (* Principles,' p. 90), which is simply begging 
the whole question at issue.'* 

But Baron Liebig has yet another way of claiming the neces- 
sarily admitted action of ammoniacal salts, as one of minerais. 
Thus he says : — 

'' Now, since sulphate of ammonia and sal-anmioniac, in the same way as 
carhcnic add, increase the solvent power of water for these e8f>ential ingredients 
of the food of plants, the question at once arises, whether their good effects 
may not depend in great part on this property, and whether, in the experi- 
ments of Mr. Lawes, the whole effect of the ammoniacal salts do not consist 
of two actions, namely, that of ammonia, as food for plants, as a ftource of 
nitrogen, and that of its suits as replacing carhonic add P The answer to this 
question may serve to reduce to its real value the assertion of Mr. Lf^wes (vol. 
xii. p. 24), ^ that it would be much nearer the truth to say that the crop has 
risen and fallen in proportion to the diminution or increase of the ammonia 
supplied to it in manure.*" — Principles, p. 91-2. 

" But if, on the contrary, only a small part of the ammonia acted by its 
nutritive property, and by far the greater part by its solvent power for pkos- 
f hates and silicates ^ its action is explained in a more satisfi^^tory manner ; for 
la this case the effect is proportional to the quantity of water ^hich entered 
the plants, and was given off by evaporation from their surface, the solvp*** 



AgricuMural Gliemiatry, 41 

power of this water for these suhdtances haying been increased by the am- 
moniacal salta. The effect of the earthy photphates and of the Bolttble silicates 
depends on the quantity of them in the soil ; their Affect in a giyen time is 
poportional to tne quantity which enters the plant in that time. This again 
is proportional to the degree of their solubility in rain-water, and to the amount 
of rain-water absorbed by the plant" 

** Both properties — that of ammonia as a nutritive agents or source of 
nitrogen, and that of the ammoniacal salts as solvents — have certainly co- 
operated to giye the increased produce ; for since the total produce, 28,431 lb& 
of grain and straw, of the lot manured with ammoniacal saltf*, was to that of 
the unmannred land, 18,122 lbs. grain and straw, as three to two, and con- 
seqnently the excess of the former was equal to half the amount of the latter, 
it is eyident that this excess must haye contained exactly as much ailicate of 

S>ta8B and phosphates as existed in one-half the crop of the unmanured land, 
ow, since ammonia cannot replace these essential constituents of the wheat- 
plant, it follows, that, by the agency of the ammoniacal salts, this entire 
additional quantity of mineral constituents was rendered soluble and avail- 
able for tiie plant. These Baits have enabled the rain-water, in equal yolume, 
to dissolye and carry into the plant, in the same time, one-half more of these 
substances than was yielded, without ammoniacal si^ts, by the unmanured 
land.'— iJ , pp. g»-101. 

We are here told, then — in March, 1855 — ^that the eflScacy of 
the salts of ammonia in our experiments is to be attributed in a 
great measure to their solvent dction on the phosphates and silicates 
of the soil ; the increase of produce being greatly due to the 
consequently increased supply of these minerals to the plant. 
The reader will imagine therefore our astonishment, when, in 
September of the same year, we heard Baren Liebig in the public 
discussion of our experiments, energetically maintain, that the 
presence in the soil of ammonia and its salts must reduce the 
solubility of the silicates I We have since found, that he had then 
already published two papers in Germany, in the course of which 
he sought to establish the latter view. We are not disposed to 
dispute the probable truth of this amended conclusion. For, in 
experiments instituted with the view of testing the probability of 
Baron Liebig's precious assumption, we had found that water 
containing salts of anmioniay when percolated through a given 
bulk of soil, dissolved less silica than piure water so percolated. 
At the same time, however, we must say, that we cannot admit 
the legitimacy of deductions from experiments made upon pure 
filicates out of the soil, as to what would happen under the com- 
plicated and little understood chemical conditions of cultivated 
soils. 

At any rate, however, we must conclude, that Baron Liebig's 
explanation of the efficacy of ammonia-salts in our experiments, 
80 far as it supposed an increased supply to the plant of silica — 
Ae characteristic mineral constituent of the crops to which 
ammonia as a manure is peculiarly adapted — ^is now abandoned ! 
But what of the phosphates ? We will neither assert nor deny, 



42 Agricultural Chemistry, 

that these important mineral constituents may be rendered more 
soluble in the soil, in a given amount of water, provided this 
water contain ammonia salts. But, whether or not the increase 
in the produce of grain and straw in our experiments, was in any 
important degree due to this cause, is quite another question. 
Upon this point some opinion may be formed from the following 
considerations : — 

How is it, we would ask — if, in the experiments where 
ammonia-salts alone were employed for a series of years, " only 
a small part of the ammonia acted by its nutritive property, and 
by far the greater part by its solvent power for phosphates " — 
how is it, we would ask, if this were the case, that the addition 
of a very much larger direct supply of phosphates than the increase 
of crop could require, indeed in an amount and in such a form 
of easy solubility as to yield extraordinary I'esults with some 
other crops than the cereals, should, with the latter, when used 
without ammonia, give scarcely any increase whatever ? In 
other words, are we to suppose a greater amount of phosphates 
to be rendered soluble from the stores of the soil itself, by the 
solvent action of the ammonia-salts employed, than by the direct 
iisey in an easily soluble forrrVy of many times more phosphates than 
the increase of crop could require ? On this point we may state, 
that the increase of produce on plot 10a contained an annual 
average of 6 to 7 lbs. of phosphoric acid ; whilst ten times that 
amount was the general dose of that acid supplied to the soil in 
our experiments when mineral manures were employed — a large 
part of it existing, when added to the soil, in that form of easy 
solubility as superphosphate of lime, which is found so efficient 
for other crops than the cereals, the remainder existing as very 
finely powdered earthy phosphate. 

Would it not be both more candid and more consistent, instead 
of thus wrestling to the last to maintain the shadow of an obvi- 
ously half-abandoned theory, to attribute the increased assimila- 
tion of minerals on a given space of ground, which is necessarily 
incident to an increase of crop, rather to a multiplication of th© 
feeders of the plants, and an increased vigour of growth under 
the influence of nitrogenous supply, which, by virtue of the 
larger amount of soil-solution which must be absorbed, enables 
them to take up with it more of those minerals which were 
obviously neither wanting nor insoluble ; although they cannot 
be assimilated by the cereals beyond a limited amount (varying 
with atmospheric supplies), unless nitrogen in an available form 
be at the same time provided unthin the soil itself? 

We proceed next to show how, the effects of available nitrogen 
supplied to the soil being necessarily admitted, the fact of its 
being thereby enabled to yield an increase of produce, is not to 



Agriadtural Chemistry, 43 

be considered as an increase of fertility ; and the farmer is 
therefore to be cautious how he adopts any such ruinous means of 
raising the produce of his land. Baron Liebig says : — 

** In that work of mine I have fully explained that the idea of fertility in a 
soil, eseentially compriies that of the oontinuaTice and duration of the crope. 
No one regards as fertile land such as, without manure, hears good croip for a 
year or two, and no more. In this point of view, the fertility of a sod is in 
oireot proportion to the conditions of fertility present in it; that is, to the 
mmerai gubstances which are necessary for the nutrition of plants.*' — Prin- 
«ipi!et, p. 75-6. 

^^ If we manure the same land with 3 cwt. of ammoniacal salts, we shall 
ha^ in one year, a crop one-half heavier than on the unmanured land ; we 
shall titeain annually one-and-half crops, or, in eight years, the produce of 
twelve a^MM^ crops. That is to say, the soil will have lost, in eight years, as 
much minenS laatter as it would have lost in twelve years without ammoniacal 
salts; it will tkwefore be exhausted, or hecome unfruitful for wheat, four 
years sooner than if tto ammoniacal salts had been used. 

" I hold, therefore, that which in my work I have endeavoured so fully 
tnd minutely to explain, that, in reference to the exhaustion of the soil, 
amnwma or ammomaoal saUSf used alone, are the kinds of manure which 
impoverish a soil, or in other worda^ consume the capital of the land, the most 
rapidly. 

" In one case only does the fertility of the soil manured with ammonia, or 
its salts, maintain itself, namely, when these are accompanied by the mineral 
substances which are annually removed in the crops. These may be restored 
either by annually adding as much as is removed, or by adding after the fifth 
crop a tive-fold quantity of them. If this be once omitted, the effect must 
hecome perceptible in a series of years. 

'* The rational agriculturist must not believe, that he can remove from a rich 
fertile soil, without any compensation whatever, a part of its constituents, vod 
not, by so doing, sooner or later impair its fertility ; for this fertility, or the 
produce in a given time, is the effect of the whole sum of the actions of all its 
constituents ; not only of that portion of them, which has entered the plants, 
but also of the rest of the available supply, which is left in the soil. The 
entire supply, or sum, has produced this result, namely, that the roots found 
evenrwhere their necessary food ; and if we remove a nart of the whole supply 
of these constituents, then the roots will no longer nnd their proper- fo<xl in 
that part of the soil where they are wanting. 

"Let us only suppose that during the last few centuries our ancestors had 
aeted on the principles here laid down, in their full extent and strictness ; 
what a paradise of fertility would England be at this day I " — lb., p. 81-3. 

We must here first notice the running insinuation in these 
passages, that we would recommend as a practice for adoption in 
agriculture generally, the continuous growth of corn by means of 
nitrogenous manures, without any other return to the land. It 
is only to those who have never read our Papers, that it is 
necessary to say, that a more incorrect impression of our views 
could not possibly be given than that which is herein implied ; 
and which is more plainly, if not more courteously, expressed 
m the following sentence : — 

** It is not easy to understand how Mr. Lawes could deduce from his results 
tbs oooclusion ' that nitro^enised manures are peculiarly adapted f^r the culr 



44 AgrimUural Chemistry, 

ture of toheaty nnoe such manures can only produce a favourable reeolt if 
certain preUnunary oonditiofiB, which Mr, Latces has entirtly disregarded^ 
be fulfilled. There could hardly be made an assertion better calculated to 
mislead the practical farmer.'* — lb,, p. 79. 

To meet these grataitous statements from snch a qnarter, it is 
necessary to repeat, then, that the whole of our recommendations 
to the farmer in this matter, have been repeatedly and elaborately 
defined, to apply to agriculture as generally practised in this 
country, that is to say, agriculture as Uis — ^the *' preliminary con- 
ditions " which we have supposed being, a cuUioated soU^ and a 
Totdtion of crops. And wiiat, then, does a rotation of crops in this 
country involve ? It involves the growth of root and other fallow 
crops ; the growth of these involves the feeding of animals on the 
farm ; the feeding of animals on the farm involves the production 
of home manure ; and the production of home manure involves 
the *' preliminary condition,'* of a periodical return from the re- 
sources within the farm itself of a large proportion of the mineral 
constituents which have been removed iix^m the land in the crops. 
Into all this we have gone with considerable detail, again, and 
again; — as well on the assumption of there being, as of there 
not being, a certain amount of imported constituents to be further 
taken into the calculation. With this explanation we will again 
apply to Baron Liebig his own words : — ** It is not difficult 
to refute the opinions of another if we ascribe to him assertions 
which he has never made." ! 

But now for the assertion that fertility is almost exclusively 
referable to the mineral richness of the soil. True, there can 
be no fertility without a liberal provision of minerals; but 
what, we would ask, is the use to the practical farmer of main- 
taining his land in a condition of so-called ^'fertility,'' which, 
without the addition of sovnething else, will yield him no increase 
of produce whatever? What, we would ask, is the use to the 
farmer, of a merely latent or reserved capability of production, 
if this latent capability be not brought out into activity and use ? 
And it is undoubtedly true, that in agriculture generally, with 
rotation, there is a considerable accumulation of this latent or re- 
served capability of production, which cannot be brought into 
activity and use for the increased growth of the main saleable pro- 
ducts of the farm — the cereal grains — without the accumulation, 
within the soil itself of available nitrogen. Again, experience shows, 
that by the production of grain, the stores of available nitrogen within 
the soil are far sooner exhausted or brought down to an annual 
minimum, than those of the minerals. How much more strongly, 
then, to be consistent, should the argument be applied against 
the exhaustion of the land of its available nitrogen! And should 
not Baron Liebig, in obedience to his own principle of rumr 



Agricultural Chemistry, 45 

exiumstianj precisely reverse the advocacy reiterated in the fol- 
lowing sentence ? — 

" I had myaelfy in the first edition of my work, Uttribated to ammonia 
a preponderatinff value and importance ; and I thought I had sufficiently cor' 
ncted this error in the mbseqztent editions," — Principles, p. 79. 

Surely, if any of the constituents necessary to the production 
of our crops, should have, in the eye of the agricultural chemist^ 
" 9, preponderating value and importance," it should be those which 
are the most easily, not those which are the least easily, exhausted 
in the course of practice ! — those by the want of which the limit to 
our production of com is in practice fixed — not those which, in 
the same course of practice, are ready and waiting, but inactive, 
dormant, and unremunerative, because unassociated with others 
which we are told should nevertheless not have attributed to them, 
" a 'preponderating value and importance " ! 

But we have not yet done with the limitations to a free and 
unqualified admission of the pre-eminent importance in agri- 
culture, of an accumulation of nitrogen in an available form within 
the soil itself: — 

" The advantage of this artificial supply of ammonia, as a source of nitrogen, 
» limited f like t<hAt derived from the presence of humus in the soil, to a gain 
of time,'*—Ib,f p. 74. 

What, we would ask, is gain of time in the growth of plants, 
but the very essence of the distinction between natural growth 
aud artificial growth, that is, agriculture ? In this admission, 
therefore, is involved the fullest and most convincing proof, that 
if any of the constituents of plants should have attributed to them 
" a preponderaiing value and importance," it should be those 
to which is due a gain of time. 

To resume: The following is a brief summary of the criti- 
cisms to which our experiments on the growth of wheat have been 
submitted by Baron Liebig, with the view of showing that their 
results are at once consistent with his own peculiar doctrines, 
and inconsistent with our own conclusions. 

He maintains alternately, that the supply of ammoniacal salts 
bas noty and has^ been the source of the increase ! And, when it 
became impossible to avoid the latter conclusion, how does he 
qualify the unpalatable admission ? 

Such a result is precisely in Ojccordance udth what theory teaches ! 

SaUs of ammonia are themselves to be included as mineral 
v^nures! 

Their action is mainly that of rendering soluble the minerals of 
^ «oiJ, and hence it is the minerals to which at last the increase is 
due ! 

If awmonio'Salls do gice increase, they do hut exhaust the land ! 



4(i Acfncalhiral Cli&inistry. 

Their action is only a gain of time ! 

And lastly, their observed effect in our own experiments is ordy 
exceptional^ so that no deductions whatever can be formed there- 
from, in regard to corn-exhaostion in any other case ! 

The point which we propose next to illustrate, by reference to 
a very condensed tabular statement of a large number of experi- 
ments is, that the provision of available nitrogen within the sail, 
has a very marked effect upon the increased growth of barley 
also — the second in importance of the cereal grains in our own 
country and climate. 

In Table II., given below^ we have the results of experiments 
on the growth of barley in the year 1854, in two separate fields 
of widely differing previous history. The portion of " Barnr- 
fieli^ the produce of which is given in the upper part of the 
Table, had grown turnips experimentally for ten successive years, 
without being manured with any nitrogenous or carbonaceous 
substance. It had, however, been exceedingly liberally sapplied 
every year, with various mineral manures; which in some 
cases included in very large excess every constituent which the 
ashes of the crop would contain. The condition of these plots, 
indeed, would be that of such exhaustion of organic substance, 
and, on the other hand, of such a repletion of mineral consti- 
tuents, as could not occur in the ordinary course of farming. 
Strange to say, however — that is, for the credit of the " mineTol 
theory*' — this exceedingly mineral-enriched, and nitrogen-impo- 
verished land, gave for the season in question an excessively 
meagre crop. In fact, its total produce (com and straw) was only 
two-thirds that of our continuously unmanured wheati-plot, and 
little more than half as much as that grown without manure or 
by mineral manure alone, in our other experimental barley-field ; 
although the crop in the latter, some of the results of which are 
also given in the Table, was the fourth of barley, and the third 
without nitrogen9us manure. Previous to the first experimental 
crop, however, the latter field had not been submitted to more than 
an ordinary course of exhaustive cropping. We have here, then, 
a remarkable instance of the utter incapability of a very liberal 
supply of mineral constituents, on a soil exhausted of organic food, 
to enable the plant to obtain sufiicient nitrogen from atmospheric 
sources, for the growth of the barley-crop in adequate agricul- 
tural quantity. Nor was there in this " Barn-field " a difference 
of more than a bushel or two, between the produce of those plots 
which had previously received large amounts of alkalies as well 
as phosphates, and those which had only been manured with the 
latter. 



AgriGuUural Cliemisfry. 



47 



Table II. — Summary of Experiments on the Growth of Barley. 
Average Total Produce (Com and Straw) per acre, in Ihe. 



General Condition of Manuring. 


Total 
Prodace. 


Total 

Increase by 

KitTDgen. 


Barn-tield— Harvest. 1854. 


Mineral Series (mean) 

Ditto (ditto) with Ammonia-salts 

Ditto (ditto) with Nitrate of Soda 


2474 
73H2 
8005 


IbB. 

4908 
5531 


Hoo8-6eld— Harvest 1854. 



Mineral Series (mean) .. 

Ditto (dii to) with Ammonia-salts. . . 

Ditto (ditto) with Rape-cake... 

Nitrate of Soda (second year without Minerals)... 



• •* ••• ••• ••• ••« 



» • • • • • 



4656 
8127 
8150 
7400 



3471 
3494 
2744 



In the Table it is seen, that the mean total produce (com and 
straw together) of barley in * * Bamrfieldy" on the previously mineral- 
manured plot, is 2474 lbs. ; that on land in similar previous 
condition, but with ammonia-salts now added, is 7382 lbs. ; and 
that with nitrate of soda instead of ammonia-salts, is 8005 lbs. 

In *' HooS'fisld " again, the mean total produce of the series 
manured annually with direct mineral manures, is 4656 lbs.; 
that with ammonia salts in addition, is 8127 lbs. ; that with 
(besides the minerals) rape-cake, equal in its amount of nitrogen 
to the ammonia-salts of the previous series, is 8150 lbs.; and 
that with nitrate of soda^ this being the second year of its appli- 
cation without mineral manure, is 7400 lbs. 

Here then, in both fields, we have an enormous increase of 
produce in the barley^ crop, by means of available nitrogen 
supplied to the soil. And although, owing to the more limited 
range of the underground feeders of the barley plant, and to the 
i9adi shorter period of time during which it collects its mineral 
food, direct mineral manures have a more beneficial influence 
upon that crop than up6n wheat, yet it is obvious, that as with 
the wheat crop so also with barley, a maximum agricultural 
produce cannot be obtained, however liberal the supply of 
minerals, unless there be, at the same time, an accumulation of 
available nitrogen within the soil itself. 

We now tui*n to a consideration of Baron Liebig's treatment 
of our recorded experiments and conclusions in reference to the 
growth of turrwps. He says : — 

" It seems to me worth while to consider here one more of those unmean- 
ing practical experiences, made by one who is, according to Mr. Pusey, the 



48 Agricultural Chemistry. 

first agricultural authority in Eugland, namely, by Mr. Lawes. It refers 
to the growth of turnips (vol. xii. p. 34, and vol. viii. part iL p. 26, et 
seq,y — Principles, p. 128-4. 

In consequence of the great length of this Paper, we must 
content ourselves on this occasion with examining only one or 
two of Baron Liebig's criticisms on this point, in that detail 
which we had intended. 

Baron Liebig attributes to us the assertion, that " phosphoric 
acid alone was found efficacious " in our experiments — ^a state- 
ment in direct contradiction to opinions strongly insisted upon 
throughout our Paper on turnip culture, fit)m which in part he 
quotes. He considers the results obtained by large quantities of 
burnt bones and sulphuric acid, as demonstrating " the existence 
of a very unusual quality of soil " ; and having thus admitted 
the fact itself, he adds : — 

'* But if we inquire into the reason why the credit of this striking result is 
given to the phosphoric acid, we find that this is a sheer Janet/. Were any 
one to assert that, under the circumstances, it was the free sulphuric avid 
which produced the result, it would he difficult to disprore the assertion, as 
will be seen from the following calculation." — Principles, p. 125. 

He then goes on to assume, that we employed in the experiment 
in question, ** as a minimum," 400 lbs. of burnt bones (and sul- 
phuric acid besides), every year, during eight successive years — 
or in all, 8200 lbs. of burnt bones ; more than enough, as he 
tells us, for fifty average crops of turnips. Now it so happens, 
that 3200 lbs. of burnt bones w a pure assumption of Baron 
Liebig's, as indeed he admits in a note ; but he does not the 
less on this account make liberal use of this assumed fact. The 
quantity of phosphate of lime used in the eight years was in 
reality more than a thousand pounds less than was supposed 
by Baron Liebig. Farther on, after having pointed out the 
excess of phosphate added in the previous years, he says : — 

''It is impossible to believe that the eflect, in the seventh year, under 
these circumstances, can have depended on the ne^ly-added phosphoric acid, 
as Mr. Lawes concludes." — lb., p. 126. 

And again — 

'* What conclusion would Mr. Lawes have come to. had he manured his 
land, for two years, only with phosphate of lime, and had added, in the six 
succeeding years, 400 lbs. of sulphuric acid alone, and ^ad be thus obtained 
tbe same produce, in eight years as if he had used 3200 lbs. of burnt 
bones ?"—/&., p. 120. 

Now it does so happen, that we have an experiment that will 
show, as far as such a point is susceptible of proof, that there 
was an action due to the large amount of phosphate of lime 
added to the soil, which could not be attributed to ** free sul- 
phuric acid" in admixture with it; and further, that a still 
greater excess of superphosphate of lime gave a further increment 



Agricu liural Ch-em intry. 



49 



of increase. In the following Table (III.)) we have the result of 
this experiment; namely, that on plot 21, which, with those on 
plots 7 and 22, given on either side of it, will illustrate the point 
in question : — 

Tablb III. — Selection of Results of Experiments on Turnips. 

Produce of Bulb per Acre. 



Tears. 


Plot 7. 
\ Cwt. Sulphate Ammonia, 

in 1843. 
3 Cwt». ground Apatite, in 

1844. 
13 Cwts. Qypsum, in 184«. 

Afterwards Unmanared. 


Plot 21. 
Saperpfaosphateof Lime, 
in 1843-4-5. 

AiterwardB TJnmanured. 


Plot 32. 
Snperphosphate of Lime, 
eveff Tear. 


i /1843 
1 1844 
^ J 1845 
^ ' 1846 
1 1847 
1 11848 


Ton& Owts. 
6 184 
3 1 
6 13} 

• • • 

2 lU 

1 o| 


Tons. Cvrt«. 

11 14} 
7 3} 

13 2 
1 5} 
3 17 
6 7} 


Tons. CwtB. 

12 3i 
7 14} 

12 13} 
1 18 
6 11 

10 11 


1 

GO 


[1849 
1850 
1861 

il852 


2^ 
4 6} 
3 10 

1 4 


15} 
8 
6 7i 
2 15| 


3 15 
11 9 
10 16} 

8 9} 


Totals ... 


28 8} 


61 9 


85 . 1} 


Means ... 


3 ^ 


6 3 


8 10} 



Plot 21 received in all, during the first three years of the 
experiment, about 800 lbs. of bone-earth, or its equivalent in 
apatite (mixed with sulphuric acid) ; and from that time it was 
nninanured. And since the whole produce of the ten years 
would only remove from the land, say one-third, of the phos- 
phoric acid added in the first three years, it is obvious that there 
must have remained in the soil a large residue of the supplied 
phosphate, for tlie seven crops grown since the application of 
the manure. 

Plot 22 had also large amounts of superphosphate of lime 
supplied to it during the first three years ; and after that time 
it received every year 160 lbs. burnt bones, mixed with 120 lbs. 
of sulphuric acid of sp. gr. 1*7. 

Plot 7, having had a small quantity of ammonia-salts in 1843, 
3 cwts. of apatite in 1844, and 12 cwts. of gypsum in 1845, 
yielded, in 1846, without manure of any kind, so small a crop 
as not to be worth weighing ; and this plot 7 was afterwards 
continuously unmanured. 

It is seen that, during the first three years of the experiment, 
plots 21 and 22, being both manured liberally with superphos- 

D 



50 Agricultural Chemistry. 

phate of lime, gave nearly equal amounts of produce; thougli 
plot 22, having rather the most of the manure, gave also rather 
a higher average produce. 

In 1846, the now unmanured plot 7 (which, however, had 
received a large quantity of powdered apatite two years pre- 
viously) yielded next to nothing; plot 21, now unmanured, but 
having a larger residue of phosphate of lime in the soil, and in 
a more easily soluble form than plot 7, gave IJ tons of bulb; 
and plot 22, with its large residue of phosphate of lime, as well 
as annual additional supply of superphosphate of lime, gave 
nearly 2 tons. 

In 1847, plot 7 gave rather more than 2^ tons ; plot 21, with 
its residue of phosphate of lime, gave nearly 4 tons ; and plot 22, 
with its additional su^pjily of superphosphate, as well as residue, 
gave rather more than 5^ tons. 

In 1848, the comparatively non-residue-plot (7) gave 1 ton of 
turnips; the residue-plot, 6^ tons; and the residue, with addi- 
tional supply, more than 10^ tons. 

In like manner, to the end of the experiment, it is seen that 
the residue-plot 21 always gives a considerable increase (varying 
according to season) over the comparatively non-residue plot 7 ; 
and again, plot 22, with both its accumulating residue and its 
additional supply, in every case gives a considerable increase over 
the residue plot 21, although the latter, even up to the last year 
of the experiment, still retained a large proportion of the pre- 
viously added phosphate, besides all that must have been avail- 
able, during the ten years, from the stores of the soil itself. 

Now it is quite certain, that on plot 7 there was much more 
phosphate supplied in the apatite in 1844, and derivable from 
the annually available stores of the soil, than was necessary to 
supply with phosphoric acid a much larger produce than was 
obtained on that plot. It is also quite certain, that the much 
larger produce on plot 21 than on plot 7 must have been due to 
the residue of the manuring of the years 1843-4-5. If any one, 
therefore, were to assert that, under the circumstances of this 
plot 21, "it was the free sulphuric acid which produced the 
result," it would certainly ru)t **be difficult to disprove the 
assertion." And again, it is certainly also true, that the further 
increase obtained on plot 22 over plot 21 must be due to the 
additional mixture of phosphate of lime, mixed with sulphuric 
acid, which was annually supplied to it. And, as we have seen 
that on plot 21, a supply of phosphate far in excess of that con- 
tained in the crop produced — ^the action of which could not be 
attributed to free sulphuric add — did give an increase, and as we 
well know that any free sulphuric acid which might reach the 
soil would in a very short time be neutralised, the reader will 



Agricultural C/imnistry. 61 

judge for himself, whether on plot 22 the increased produce 

obtained was more probably due to free sulphuric acid, or to the 

still greater excess of phosphoric acid or its compounds supplied 

in the manure ; — that is to say, whether the increased produce on 

plot 22 was not due to an action very similar in kind to, but 

differing in degree from, that on plot 21 ? 

Again, Baron Liebig says — 

*' If we continue our examination, we shall find, still in bis own experi- 
ments, much more convincing proofs that the excess of phosphoric acid 
cannot have been the cause of the increased produce." — Principles, p. 126. 

He then goes on to institute comparisons which, taking the 
figures simply as they stand, and without the explanations of the 
very results in question given in our papers, were certainly well 
calculated for his purpose, if the only object he had in view were 
to mystify, misrepresent, and fix contradiction upon agricultural 
phcDomena. Thus, following up the incorrect assertion that " phos- 
phoric acid alone was found eflScacious " in our experiments, by 
assumiug that we should measure the action of farm-yard manure 
or rape-cake, by the quantity of phosphoric acid or phosphate of 
lime they contained, he goes on to compare the produce by these 
manures, sometimes in the same year, and sometimes not, with 
that by superphosphate of lime alone ; and then he says, in 
regard to these results, " in what incomprehensible contradiction 
do they stand to the opinions of Mr. Lawes ! " One quotation 
alone from our paper, to which, indeed, but for the length of this 
article, we had intended to add many more, will show not only 
whether we maintained that phosphoric acid alone was efficacious^ 
but whether or not it was to the phosphoric acid they contained, 
that we supposed the action of farm-yard manure and rape-cake 
was chiefly or only due.* Thus we say, speaking of superphos- 
phate of lime— 

* Asa further instance of the spirit and fairness of Baron Liebig's criticisms, 
he speaks of the " unpardonable blunder" of using rape-cake as a carbonaceous 
inaiiiire,->because, as he says, it contains a large amount of nitrogen also; on 
which point he quotes the analyses of Mr. Way. Those who have not read our 
Plapers, would scarcely think it possible, that we have again and again spoken 
in them of the amount of nitrogen in rape-cake ; and frequently also, parti- 
colarly contrasted the effects of rape-cake and other organic manures, with 
that of ammonia-salts, in order to eliminate the action of the nitrogenous and 
carbonaceous supply respectively. But, Baron Liebig equally ridicules us, for 
using experimentally, rute and oil : substances chosen as containing little or 
no nitrogen. One of the carbonaceous manures by which he obtained his re- 
sults, was sawdust. His anxiety to ignore that we attribute an action to car- 
bonaceons manures, and to ridicule all our experiments connected with such 
nuBiures, is however perfectly intelligible, when it is borne in mind, that he 
claims to have embodied in his '* 14th Proposition," a correction and enlarge 
9ent of his views. That Proposition is, he says, the only one of the 50 given 
in his *PrinekfleSt the substance of which is not to be found in his previous 
works; and the oi)ject of that Proposition is to claim an action of animal and 
vegetable manures, by virtue of the organic tuhttance they contain. We shall 
however have occasion to show, in on« striking instance at least, and we oould 

d2 



52 



Agricultural Ch^mish'y, 



" The latter manure is the form which is found to produce the p^reatest 
effect upon the young plant, and especially upon the development of a huige 
amount of fihrous roots. . ... It must, however, be dearly understood 
that the bulk of an agricultural crop of turnips depends materially vpon the 
amount of organic matter contained in the soil, without which the development 

of the poxoer of growth by means of the pho^hate will be imavaiUng 

Rape-cakef as containing a large amount of organic matter, is an admirable 
manure for the turnip as a substitute for farm-yard dungj* — Jour. Roy. Agr. 
Soc, Eng. vol. viii. part ii. pp. 662-8. 

We cannot now stop to point out various little discrepancies 
in Baron Liebig's professed quotations of figures ; but there is 
one result, which he says is ** still more incomprehensible," to 
which we must call attention. In this particular instance, we 
cannot entirely blame Baron Liebig, for it is a misprint in our 
own paper, that has supplied him with the strong point of his 
case; though, the evidence respecting the same experiment 
given in the immediately succeeding tables, would have saved 
any careful critic, from the blunder into which he has been 
led by the misprint. He quotes a plot manured with gypsum 
and rape-cake in 1845, and apparently yielding 18 tons I cwt. 
of turnips. Now it so happens, that in our paper, we spoke 
of the produce of the farm-yard manure of that year, which 
was 17 tons, as the highest in the entire series of the experi- 
ments. This certainly ought to have raised some doubt as 
to the correctness of the figures in question. The fact is, 
that instead of 18 tons 1 cwt. the produce was only 10 tons 
1 cwt. ; and this was shown by the relation of the average weight 
of bulbs and number of plants per acre, and by that of the acreage 
produce of leaf, and the proportion of the latter to 1000 of bulb, 
as given in the tables which immediately succeeded. 

To say nothing of minor discrepancies which also appear, the 
following is the curious contrast which we obtain, between Baron 
Liebig's comment, and that which is really consistent with 
the facts of the case. In the left-hand column is given Baron 
Liebig's comment, founded on the misprint ; and in the right- 
hand one, the comparison is shown as it wotUd he, according to 
the corrected figures. The italics are given to indicate the dif- 
rerences between the parallel passages in the two cases. 



Principles, p. 127-8. 
" In 1845, another lot of equal size, 
manured with 12 cwt. of gypeum 
(the residue of the manufacture of 
tartaric acid), and 10 cwt. of rape- 
cake, yielded 18 tons 1 cwt. of tur- 
nips, that is, 6 tons more than the 
highest produce (12 tons) of the land 



Amended Comparison. 
In 1845, another lot of equal size, 
manured with 12 cwt. of gypsum 
(the residue of the manufacture of 
tartaric acid), and 10 cwt. of rape- 
cake, yielded 10 tons 1 cwt. of tur- 
nips, that is, 3 tons 1} cwt. less than 
the highest produce (13 tons 2) cwt.) 



in others, that < Proposition 14 * is not the only one, 'which records an advance 
upon Baron Liebig's previous views. 



Agricultural Chemistry, 53 

naniued with bones and Bulphuric of tbe land manured with bones and 
srid, and nearly 10 tons more than its sulphuric acid, and only 1 ton 16 cwt. 
average produce, or more than double more than its average produce, which 
of this last, which was 8^ tons. " was S| tons. But, yypmm toithout 

rnpe-cake gave 7 tons 9 cwt. lees than 
the highest by superphosphate of lime 
in the same year ; and 2 tons 1 1 cwt, 
less than the average produce of the 
latter I 

Baron Liebig's numerical comment on this ** still more inco^i- 
prehensible " result is therefore simply reversed. But let us now 
see how far his comparison was legitimate, even supposing his 
numbers had not been erroneous. The real fact was, then, that 
g3rp6um used aloney though even afber apatite (phosphate of lime) 
in great excess in the previous year, gave only 5 tons 14 cwt. of 
produce. This, as the result of purely mineral manure, was 
that which, in fairness^ should have been compared with the 
"12" or rather 13 tons 2 J cwt. yielded by the phosphate of 
lime and sulphuric acid in the same season. Again, 7 tons 
10 cwt. was the produce of 10 cwt. of rape-cake^ when, used alone ; 
and when to this latter amount is added, that portion of the 5 tons 
14 cwt. by gypsum alone, which may be supposed not to be due 
to the previous dressing of finely powdered apatite, there is cer- 
tainly nothing anomalous in the fact, that the gypsum and 
rape-cake together, gave 10 tons 1 cwt. of turnips. 

It is, then, after such comparisons as those which we have 
pointed out, and on an incorrect statement as to our conclusions, 
that Baron Liebig says of our results, '^ In what incomprehen- 
sible contradiction do they stand to the opinions of Mr. Lawes ! " 
And he adds — 

''It is out of the question, after the facts just related, to assume that tbe 
exoefls of phosphoric acid was necessary, and was the cause of the increase. 
Is it then the sulphuric acid, the Ume, or both together (gypsum), or is it 
the organic matter in the stable manure and in the rape-cake ? " — Principles , 

To this we answer — that, where the superphosphate of lime was 
ned, " it is out of the question after the facts just related," to 
doubt, that the action of '' the excess of phosphoric acid," or of 
the phosphate of lime, '* was the cause of the increase," in that 
particular ease ! — or, that where the farm-yard mamiwre or ra/pe" 
cake was used^ '' the organic matter in the stable-manure and in 
the rape-cake," together with the mineral constituents they con- 
tained, played an important part in providing the actual sub* 
stance of the increased crop. 

What, then, is the result of our examination of Baron Liebig's 
criticism on our experiments and conclusions regarding the growth 
of turnips ? It is seen — that his statement of our general concln* 
6ion is incorrect ; that his allegation as to the amount of phosphate> 



54 Agricultural Cfiemistry, 

of lime we used is an assumption and erroneous ; that his objec- 
tions to admittiDg an action by an apparent excess of phospbabes 
are captious and unfounded ; that his '^ incomprehensible " fiskcts 
are comprehensible and coTisisierd ; and that his ^' still more incom- 
prehensible " fact is not even a fact at all, but is founded only 
on an easily discoverable misprint ! 

But after all this strenuous resistance of the notion, that in the 
agricultural — ^that is, in the artificially enhanced — growth of 
plants, there may be required a supply of substances by manure, 
beyond that which can be accounted for by any idea of merely 
supplying what is to become an actual constituent of the removed 
crop — and saying with regard to it, *' have we made, after all, 
but a hair-breadth's progress from our old position ? " — we find, 
but a page or two further on, the enunciation of a general prin- 
ciple, obviously intended to cover any such instances which it 
may be impossible to deny the existence of as facts. Baron 
Liebig says : — 

'' As a general rale, the manuring of a field should not be calculated from the 
sum total of the mineral ingredients which the plant takes from the soil, but 
must be proportional to that maaimum of these substances which is requiredhy 
the plant in a certain period of its growth^ — I*rinaples, p. 133 (note). 

We would compliment Baron Liebig on the fact, that we have 
here evidence of more than " a hair-breadth's progress fix)m our 
old position," when we contrast that which is herein involved, 
with his general conclusions on the subject of manuring, in sum- 
ming up his general retrospect, in the fourth and lasl; edition of 
his main work, where he says : — 

" By an exact estimation of the quantity of ashes in cultivated plants 
growing on various kinds of soils, and by their analysis, we will learn those 
constituents of the plants which are variable, and those which remain con- 
stant. Thus also we will attain a knowledge of the quantities of all the 
constituents removed from the soil by different crops, 

" The fermer will thus be enabled, like a systematic manufacturer, to hare 
a book attached to each field, in which he will note the amount of the various 
ingredients removed from the land in the form of crops, and therefore how nmch 
he must restore to bring it to its original state of fertility. He will also be 
able to express in pounds weif^htf how much of one or of another ingredient qf 
soils he must add to his own land, in order to increase its fertility for certain 
kinds of plants:*— 4th Edition, p. 212, 213. 

And then again, to cover by general principle, the undoubted 
fact, that the resultant requirements of land under cultivation, are 
certainly not to be ascertained by the consideration of the collec- 
tive mineral composition of the crop to be grown, we are told: — 

" The produce of a field stands related to the amount of that mineral in- 
gredient which its soil contains in smallest quantity,** — PrirunpleSt p. 133 
(note). 

And this simply common-sense notion (provided that smallest 
quantity be too small for the requirements of a maximum growth), 



Agricultural Chemistry. 55 

bat which, however, is the clear way of escape firom his previous 
applications of his doctrineR, and a net large enough to include 
many now established facts inconsistent with those applications, 
is insisted upon much more at length in Baron Liebig's recent 
reply to the criticisms of his ** Principles " by Professor Wolff. 

In like manner, the careful reader will observe throughout all 
Baron Liebig's writings in this discussion, that, whenever there 
is a fact to be admitted^ or a deviation from the exact expression 
previously given to his views to be conceded, we are first fa- 
Tonred with a general or abstract statement ; perhaps obviously 
true, and perhaps so little differing from previous forms of ex- 
pression in individual sentences of his works, as to pass unobserved, 
and yet sufficient to claim the fact or conclusion which he has 
to record and admit, as but an obvious consequence. The toU 
lowing is a further illustration of this mode of ignoring the ex- 
perimental evidence and conclusions of others, and of netting 
the whole as an obvious consequence from his own principles. 

The reader need scarcely be reminded of Baron Liebig's argu- 
ment on Boussingault's rotations, viz., that the nitrogen of his 
manure had done nothing ; and that if the latter had been 
bamt, and its nitrogen expelled, the produce would have been 
the same ; — that, in defining agriculture as distinguished from 
normal vegetation, he has said, that the nitrogen yielded to the 
latter by the atmosphere was " quite aufficierUfoi' the purposes of 
agriculture " ; — and that, speaking of produce grown under cul- 
tivation, that is, in agricultural quantity, he has said — '^ Surely 
the cerealia and leguminous plants which we cultivate must 
derive their carbon and nitrogen from the same source whence 
the gramineaa and leguminous plants of the meadows obtain 
them ! " But what are we now told ? And how is the very opposite 
of this, the clear recognition of which we have maintained to be 
the very key to advancement in agricultural science, now swept 
into accordance with Baron Liebig's own principles by general 
uid abstract statements, obviously true, and put apparently with 
little reference to any point in dispute ? 

"But the guantiti/ or amount of produce is in proportion to two factors, 
namely, the atmospheric food of plants, and their terrestrial or mineral food. 
This quantity depends on the presence of both, and on their co-operation in 
due proportion, and iu the proper time. 

"If the amount of one of these factors — the mineral food of plants —be 
increased, while that of the other — the carbonic acid and ammonia, which 
can be conveyed to the plants by means of the atmosphere — remain unchanged, 
the amount of carbonised and nitrogenised produce cannot thereby increase ; 
but the crops, in this case, will vary with the absorbing or active surface of 
the plants cultivated on the land." — Principles, p. 76. 

He then goes on to state that '^ the air contains a very limited 
amonnt of carbonic acid and ammonia/' and that — 



1 



56 Agricultm'al Chemistry. 

" It is obvious that, if we could double or treble the proportion of caibonic 
acid and ammonia in the air, the plants would, in the same circumstanoesy 
take up twice or thrice as much carbonic acid and ammonia in the same tiaie, 
or as much as they could do in the normal condition in twice or thiioe tk« 
time."— i5. 77. 

Here, then, we are told, that the supplies of carbonic acid and 
ammonia in the atmosphere, though enough for normal vegeia^ 
tion, are " very limited." Surely, however, they still remain as 
before, *' quite sufficient for the purposes of agriculture " ? Baron 
Liebig answers this question thus : — 

** But the weight or amount of the crops is in proportion to the quantity 
of food of both kinds, atmospheric and mineral, wnicn is present in the scil^ 
or conveyed to it in the same time. By manuring with ammtmiacal salts a 
soil rich- in available mineral constituents, the crops are augmented in the same 
way as they would have been \f we had increased the proportion of amimonia 
in the airr-^Jb. 77, 78. 

How neatly, then, has Baron Liebig here begged the whole 
question of the necessity in agriculture as distinguished from 
natural vegetation, of an accumulation of available nitrogen 
within the soil itself! How curiously, too, are the very circum- 
stances, under which we have previously been told that our crops 
are the most capable of relying upon the atmosphere for their 
nitrogen — namely, those of mineral richness — nx/w made the very 
conditions under which the supply of ammonia to the soil is 
most necessary ! Thus, speaking of the supply of ammonia, he 
had before said — 

" that it may be even superfluous, if only the soil contain a st^fflcient suppfy 
of the mineral food of plants, when the ammonia required for their develop- 
ment will be furnished by the atmosphere."— 4M edition, p. 212. 

And again :— 

'' If the soil be suitable, if it contains a sufficient quantity of alkalies, 
phosphates, and sulphates, nothing will be wanting ; the plants will derive 
their ammonia from the atmosphere as they do carbonic acid." (I) — Trans^ 
latum of Letter, Farmer^s Magazine, vol. xvi. p. 611. 

But not only does Baron Liebig do this, but he claims it as 
the established principle of his previous writings, that it is for 
'^ wheat " distinctively, that ammonia must be added in the 
manure. Thus he goes on to say : — 

" This is the meaning of the passages above quoted firom my work, which 
tell the agriculturist that, in order to raise the produce of his land above a 
certain point, in the case of such plants as have not many leaves— ;/br ex- 
ample, of wheat — he must add ammonia in the manure.*' — Principles, p. 78. 

Here, then, the importance of nitrogen in the soil for wh^aiy as 
distinguished from other crops, is claimed as a conclusion esta- 
blished by " the passages above quoted." But strange to say, 
after thus attempting to claim that which is now so far an 
established fact, that it would be only ridiculous to deny if, 



Agt'icultui'al Cheinistry^ 57 

Baron Liebig in the very next page, when the object is to refute 
our statements, and not to claim the truth as his own, says : — 

''It 18 not easy to imderstand how Mr. Lawes could deduce from bia 
leaults the conclusioiii * that nilrogenised manures are peculiarity adapted for 
tke culture of wheat/ ...."! 

Now, it BO happens, that in "the passages above quoted," 
not one word was said of such plants as have not many leaves 
— "for example, of wheat,** The reference was to annuals 
generally; and runs thus — "The food contained in the atmo- 
sphere does not suffice to enable these plants to obtain their 
maximum of size in the short period of their life." These 
plants, the annuals^ include of course equally " cerealia and the 
legumivjous plants which we cultivate^** of which Baron Liebig 
has told us, that surely they "must derive their carbon and 
nitrogen from the same source whence the gramineae and legu- 
minous plants of the meadows obtain them." But notwith- 
standing that Baron Liebig has told us in so many forms in his 
previous works, that the nitrogen supplied by the atmosphere is 
sufficient for the purposes of agriculture, and also that the cereals 
and leguminous crops of our rotations are equally independent 
of nitrogen in the soil with the meadows, he now tells us that 
his meaning in those previous works was, that— for the growth of 
certain plants — " for example, of wheat " — the agriculturist must 
add ammonia in the manure ! The reader will judge for himself 
then, how far it is candid, or just, or strictly consistent with 
truth, that Baron Liebig should now seek to include by a state* 
ment of general principles, and by stretching and explaining the 
meaning of individual sentences of his previous works, facts and 
conclusions since established ; and which are not only funda-^ 
mejUai, as leading to the true explanation of the main features of 
agricultural practice, but which are further flatly contradicted by 
other individual sentences of his works, and are, by the concur- 
rent testimony of every competent writer on the subject, incon- 
sistent with the maiUf p'ominsrd, and most characteristic features^ 
of his previously promulgated doctrines ? 

Another instance of this kind will come to light, in consi- 
dering Baron Liebig's comments on that part of our criticism 
of his views, which led to the attack on our experiments and 
conclusions in reference to the growth of turnips. In one of our 
papers we had said : — 

" But it is at any rate certain that phosphoric acid, though it forma so 
"^ a proportion of the aah of the turnip, haa a very striking effect on ita 
growth when applied aa manure; and it is equally certain that the extended 
c^Uvatioo of root crops in Great Britain cannot he due to the deficiency of 
this tubetance for the growth of com, and to the less dependence upon it of 
toe root crops, aa supposed by Baron Liebig." — Jour, Roy. Ayr. Soc» Eny., 
vol. xii., part i. p. 36. 



58 Agricultural Chemistry. 

This comment we had made in reference to a sentence in 
Baron Liebig's '* Letters," wherein, speaking of the exhaastion of 
phosphate of lime and alkaline phosphates, by the sale of flour, 
cattle, &c., he says : — 

'' It IB certain that this incessant remoyal of the phosphates must tend to 
exhaust the land and diminish its capability of producing grain. The fields 
of Great Britain are in a state of progressive exhaustion from this cause, as 
is proved by the rapid extension of the cultivation of turnips and mangold 
wurzel — plants which contain the least amount of the phosphates, asd 

THEREFORE REQUIRE THE SMALLEST QVAKTITT FOR THEIR DEYELOPMSNT." — 

Letters, drd edition, p. 622. 

On this sentence we further commented thus : — 

" Now, we do not heatate to say that, however small the quantity of 
phosphates contained in the turnip, the successful cultivation of it is more 
dependent upon a lar^e supply of phosphoric acid in the manure Uian that 
of any other crop." 

Baron Liebig thus meets these comments, — 

" No one surely can believe that my statement as to the very small pro- 
portion of phosphates in turnips is untrue, because Mr. Lawcs has misunder- 
stood the meanmg of the sentences above quoted from my work. My Temarks 
had no reference whatever to the manuring of turnips, but were designed to 
direct attention to the difference between turnips and other crops which 
require in certain periods of their growth more poosphates than turnips do. 
With reference to the cultivation of grain, I wished to show that the growth 
of turnips had acquired so vast an extension [the italics are Baron Liebig's 
own! /or this reason, namely, beoau^se the soil loses so little of the phosphates 
by tie cultivation of the latter crop. Turnips are so advantageous in a 
rotation, only because, whatever be the quantity of phosphates contained in 
the soil, or added to it in the manure, they leave in the soil so large an 
amount of these indispensable salts for other crops, which require a larger 
Bapply of them." — Principles, p. 131. 

Further on, Baron Liebig refers the reader to the letter in 
question, to justify the meaning which he has now given to his 
sentence, and to convince him that we do not do him justice. 
Now we must say, that we have carefully re-perused that 
letter ; and still maintain, not only that if language has any 
meaning at all, we have done Baron Liebig entire justice in the 
interpretation of his sentences which we have given of them, 
but that, by no interpretation of language, can the meaning which 
he now claims be given to his argument as formerly put forth. 
Certainly nowhere have we previously been told by Baron Liebig 
that— 

" Turnips are so advantageous in a rotation only because whatever be the 
quantity of phosphates contained in the soil, or added to it in the manure, 
they leave in the soil so large an amount of these indispensable salts for other 
crops which require a larger supply of them." 

Baron Liebig's statement was, not only that turnips were 
" plants which contain the least amount of the phosphates," but 
that they " therefore require the smallest quantity for their develop- 



Agricultural Chemistry, 59 

ment." Whereas onr own statement is, that, however small the 
amount of phosphates contained in a removed crop of turnips, 
they require a large amount for their development. And if it be 
really a well-established fact, that, however small may be the 
quantity of phosphates lost to the farm by the growth of turnips, 
still a much more liberal supply is required in the soil for the 
production of a full agricultural crop of them than of com, it is 
then obvionsly impossible, that the progressive exhaustion of 
the phosphates, could be the cause of the extended cultivation 
of the former. In fact, there can be no doubt, that such an 
exhaustion would be a far greater obstacle to the extended 
growth of roots than of com. 

But with regard to the effects of an artificial supply of phos- 
phates, upon the increased production of com. Baron Liebig 
further says : — 

" We believe that the importation of 1 cwt. of auano is equivalent to the 
importation of 8 cwt. of wheat ; the hundredweight of guano assumes in a 
time which can be accurately estimated, the form of a quantity of food 
conespondinir to 8 cwt. of wheat. The same estimate is applicable in the 
valuation of bones. 

" If it were possible to restore to the soil of England and Scotland the 
phosphates which during the last fifty years have been carried to the sea by 
the Thames and the Clyde, it would be equivalent to manuring with millions 
of hundredweights of bones, and the produce of the land would increase one* 
third, or perhaps double itself, in Jive to ten years, 

" We cannot doubt that the same result would follow if the price of the 
gmno admitted the application of a gttantity to the surface of the fields, con- 
tandnff as much of the phosphates as have been withdrawn from them in the 
same period/* — Letters, Srd edition, pp. 623, 624. 

How far the increase in the produce of wheat by the use of 
guano, is measureable by the amount of phosphates it supplies^ 
the practical farmer may judge from the fact, to which we have 
before called attention, namely, that 1 cwt, of Peruvian guano will 
supply as onuch phosphoric acid as would be contained in about 18 
hushels of wheat and their equivalent of straw, say 1800 lbs. ; and 
that of nitrogen, I cwt. of guano will contain ahout as much oa 
11 hushels of wheat and 1100 Ihs, of straw. But, if we were to 
assume, that one-third to one-half only, of the nitrogen supplied 
in manure for the growth of wheat will be obtained in the in-* 
crease produced, we should have on this calculation, 4 or 5 
bushels of com, and their equivalent of straw, by the use of 
1 cwt. of guano. We leave it with the practical man to judge, 
whether these last amounts, or 18 bushels of com with their 
equivalent of straw, are more nearly those which in practice he 
obtains, by the use of 1 cwt. of guano. 

Baron Liebig proceeds : — 

^* If a rich and cheap source of phosphate of lime and the alkaline phos- 
phates were open to England, there can be no question that the importation 



60 Agricultural Chemiairy, 

of foreign com might be altogether diftpensed with after a short time. For 
these materials England is at present dependent upon foreign conntnes, and 
the high price of guano and or bones preyents their general application, and 
in sumcient quantity. Every year the trade in these suDstanoes must 
decrease, or their price will rise as the demand for them increases. 

*' According to these premises, it cannot be disputed, that the annual ex- 
pense of Great Britain for the importation of bones and guano is equivalent to 
a duty on com : with this differonce only, that the amount is paid to foreigners 
in money." — Letters, 3rd edition, p. 524. 

Now, that the efficacy of guano for the production of com^ is 
measurable by the amount of nitrogen, and not by that of the 
phosphates which it contains, is obvious from the simple facts, — 
that guano rich in nitrogen and relatively poor in phosphates, 
will command twice the price of one rich in phosphates and poor 
in nitrogen, — and that all experience shows, that the dearer 
guano, rich in nitrogen and relatively poor in phosphates, yields 
a far greater increase of grain, than that which is cheaper and 
contains more of phosphates and less of nitrogen. But, with 
regard to Baron Liebig's supposition, that if a rich and cheap 
source of phosphates were open to England, we might soon be 
independent of foreign com, — since we now have sudi a source, 
this opinion is worth a little examination. It is probable, that 
from 20 to 25 per cent, of the com consumed in this conn- 
try, is imported. Unless, therefore, a very much larger breadth 
of land were brought under com, it is obvious that, to attain this 
happy result, the whole of our wheat-fields must yield from one- 
fourth to one-third more produce than at present. Whether or 
not it is likely that they would do so by the use of phosphates, 
even if mixed with alkalies, provided that available nitrogen 
were not at the same time added, the results not only of our own 
experiments, but the experience of every farmer who has ever 
usQd an artificial manure, will at once decide. 



Fourthly. We proceed to illustrate, by condensed summaries 
of an immense mass of experimental results, and a very rapid 
consideration of their indications, some prominent points con- 
nected with the action of manures on the different crops of 
rotation, and with the chemical circumstances involved in fallow 
and a rotation of crops itself. The first of these points, namely, 
the characteristic action of certain constituents of manure, upon 
the most important crops grown in our rotations, is illustrated 
in Table IV. which follows ; and, for the purpose in question, 
wheat and ba/rley have been selected as cereals ; turnips as a 
root-crop ; and beans and clover as leguminous crops. 



TabaI 



Agricultural Chemistry, 



61 



Table IV. 

Summary — showing the characteristic action of Manures on different Grope. 

Average Increase of Produce per Acre. 



OonrtltasDts uf 9f anare 
(aaed wpantdij or combined). 



1. Potan 

1 Fotaas, soda, and magnesia . . . 
1 Saperphoephate of lime .... 
4. Do. do. and potaas . 

f . Ntferste of soda 

%. Ajnmonia salts 

7. Ammonia salts and snperphos- 1 
pbateofllme I 

8. Ammonia sal tSfPotasB, and super-) 
phosphate of lime [ 

I. Ammonia salts, potass^soda, mag- ) 
nesift,Bnd saperphosphateof lime f 



Cereals. 



Wheat. 



Barley. Beans. 



Leguminons 
Crops. 



CoTei 



Boots. 



Turnips. 



Woburn. 



lbs. 



1640 



1767 



Holkham. 




Rothamsted. 


lbs. 

• • 

•  

• • 

• • 


lbs. 

270 

414 

97 


lbs. 

• • 

none. 
342 

• • 


lbs. 

938 

813 

none. 

605 


lbs. 
1017 
1221 
113 
1580 


1443 


2882 

1714 


1870 
3317 


14 


• • 

none. 


 • 


2611 


2838 


176 


none. 


• • 


2966 


• • 


860 


1086 


3367 


3035 


8164 


1867 


926 



7 
6 



I' 



6^ 

8 16{ 

9 16^ 

10 13| 



Each entry in this Table (IV.) indicates the average increase 
per acre, calculated from all the eligible cases, throughout the 
entire series of experiments with the different manures and 
crops, and extending in most cases over several seasons. The 
method of the estimation is as follows : — ^namely, to find the 
increase in each case, or average of a number of cases, occurring 
in any particular season, by deducting from the total produce by 
any particular constituent or constituents of manure, that obtained 
without manure in the same season ; and an annual average is 
then taken of the increase thus obtained for the several seasons. 

In such a summary as is here given, we cannot expect exact 
numerical consistency in apparently similar cases, the results 
being frequently the average of very different seasons ; but we 
cannot fail to find prominent indications of the broad and 
characteristic efiects of the respective manurial constituents or 
combinations on the respective crops. And, since in all cases 
(unless otherwise mentioned) the indications are derived from 
the growth of the crop in the manner described through several 
consecutive seasons, the characteristic exhaustion or requirements 
of the several crops, is thus very prominently brought to view. 

The manurial conditions enumerated in the first column of the 
Table, may be further explained, thus : — 

Pot<iS8j soda, and magnesia — generally as sulphates. 

SwperphosphaJbe of lime — bone ash, mixed with water, and 
decomposed by three-fourths of its weight of sulphuric acid, 
■Pgr. 1-7. 

Nitrate of soda — commercial- 



62 Ayricultural CItemistry. 

Ammonio'Salts — generally an equal mixture of the sulphate 
and muriate. 

As already stated, the crops brought into this review, are 
wheat, barley, beans, clover, and turnips. In the case of wheat, 
barley, and beans, the figures represent the total increase, in- 
cludiug both com and straw ; in that of clover the increase is 
given for the sake of comparison, in somewhere about the same 
state of dryness as the com crops, that is, to the weight of the 
dry matter, one- sixth is added for water ; and that of turnips 
includes both leaf and root in the fresh state as weighed. 

At an earlier page, we have called attention to the fact, that 
Baron Liebig being obliged to admit the influence of nitro- 
genous manures in yielding an increase in wheat in the experi- 
ments on our own land, asserts that such a result is simply ex- 
ceptional ; and that from it no conclusion can be formed as to 
what would happen on any other lands of diflFerent quality. On 
this point he says : — 

'^ Had Mr. Lawes asserted that on his land, in the ^ven circumstances, 
ammonia and ammoniacal salts were found to be peculiarly favourable to the 
growth of wheat ; and that, leaving the price out of view, these salts, under 
similar circumstances, formed the best manure, he would simply have con- 
firmed a result predicted by theory. But even if his assertion had been given 
as an entirely new discovery, there could have been nothing urged against it. 

** If, however, we extend his conclusions to any other land of diiiei^snt 
quality, and placed in different preliminary conditions, it will appear entirely 
erroneous ; for it can be proved, in the same way, and by facts equally de- 
cisive, that ammoniacal salts alone, in thousands of wheat-fields, do not in 
the smallest degree increase the produce; and that, in thousands of other 
such fields, these salts do increase the produce for a year, or for two years, 
and that then a farther application of them to the same land is found to be 
utterly without effect.*' — Principles, pp. 79, 80. 

" The rebults of Mr. Lawes have no value for his next-door neighbour, nay, 
they have no value for himself; for the recipe, to which he comes, only 
applies to his own lands, and to them only in so far as experimented on, and 
only for a very limited number of year*».** — Ih,, p. 106. 

'' It is altogether incomprehensible that it snould never for one moment 
have occurred to Mr. Lawes, that in Germany, France, and even England, 
all land has not the quality of his land."— 76., p. 120. 

Now we have already shown, that whatever the natural quality 
of our own land, and whatever the amount of its annual produce 
under the influence of natural soil and season supplies, it was 
nevertheless, in an agricultural sense, in a state of com-exhans- 
tion, induced by the growth of a succession of crops in the 
ordinary course of farming, but without receiving any manure 
after the commencement of the course. It was, indeed, brought 
into such a state, that its produce was very far below that which 
might have been obtained by the ordinary means of restoration. 
We further maintain, that the nature of the exhaustion which 
the results of these experiments showed our field to have un- 



Agricultural Chemistry. 63 

dergone, is precisely that which all experience shows (and we 
have perhaps opportunities of information on this point second 
to none) to be the characteristic exhaustion induced by the 
growth of grain in an ordinary course of rotation with home- 
manuring. Upon the truth of this statement, which no results 
of direct experiments on individual soils would, we suppose, be 
admitted to substantiate, we are content to rest the credit and 
?alidity of our conclusions generally. More than tliis, however, 
as insinuated by Baron Liebig, — namely, that we would recom- 
mend the application of ammonia-salts alone, on all soils, and 
for the continuous growth of com as an agricultural practice- 
ire have never done,* 

Some of the results in Table IV. will, however, distinctly 
show, that the " recipe," as Baron Liebig calls it, to which we 
come, is not only applicable to our " own lands, and to them 
only in so far as experimented on," but that this so-called 
"recipe" is applicable to ** other land of different quality." 
Thus, under the head of ivheat, we have in the Table the results 
obtained by the use of ammonia-salts, both use^d alone and with 
a foil supply of minerals, not only on our own land, but on 
that of the Duke of Bedford at Woburn, and of the Earl of 
Leicester at Holkham ; and, as will be seen by the description 
given below, the character of the soil in these two cases differed 
very widely, both from each other, and from our own. In some 
particulars, indeed, especially at Woburn, the description of land 
is such, that if it were possible to get from any ordinary culti- 
vated soil, a result inconsistent in the main with our own, we 
should, according to the notions of Baron Liebig, be led to anti- 
cipate that it would be here most manifest. 

The soil upon which the experiments at Holkham were made 
is described by Mr. Keary, as a " Hght, thin, and rather shallow 
brown sand-loam," but " resting upon an excellent marl, which 
contains a large quantity of calcareous matter." Mr. Keary adds, 
that he finds these light sand-loams, with the above subsoil^ '' to 
be most productive and grateful for high-farming" 

Mr. Baker describes the land allotted to the experiments at 
Woburn as follows : — 

" The laud these experiments are upon is what I consider a very poor 
dsBcription of Mind, on a particulariy wild sandy subsoil. . . . The land 
^ been farmed on the foup'course system, I think I may say for twenty-five 
76&n, and previous to that was open heath-land. This, as you are aware, i» 
^ fifth 9ea9on the plots have had wheat upon them in succesmonJ" 

Now, if it were possible to find a soil under ordinary culti- 

* On this point, see Report of Bxperiments on the Continuous Growth of 
^eat at Holkham Park Farm, in the last number of the Journal of the Royal 
Agricultural Society. 



i 



6i Agricultural Chemistry. 

vation, which, according to the sappositions of Baron Liehig, 
would not give an increase of wheat by the use of ammonia-salts 
alone, and that would, after one or two years, be strikingly bene- 
fited by the application of mineral manures, it would be such a 
one as has been last described. Let as see what are really the 
facts of the case. 

By the use of ammonia-salts alone, an average total increase 
was obtained of com and straw, per acre, at Wobum of 1640 lbs., 
at Holkham of 1442 lbs., and at Rothamsted of 1714 lbs. And 
when to the ammonia-salts a liberal supply of minerals was added, 
the total increase was at Wobum 1757 lbs., at Holkham 2357 lbs., 
and at Rothamsted 3035 lbs. 

As the seasons in which these results were obtained were not 
the same in all the three cases, no precise quantitative com- 
parisons can be made. But it is a curious fact, that the soil at 
Holkham, which is described as having at any rate a good sub- 
soil, was more benefited by the addition of a full supply of 
mineral constituents, than that At Wobum. And again, the soil 
at Rothamsted, assumed by Baron Liebig to be so exceedingly 
rich in minerals, gave a greater increase by the combination of 
minerals with a large supply of nitrogen, than was obtained in 
either of the other cases. 

It is established, then, by direct experiment, that the *' recipe " 
to which we come, is not applicable only to our '^ own lands, and 
to them only, in so far as experimented on." And also, that if 
we extend our conclusions to ** other land of diflFerent quality," 
they are not necessarily *' entirely erroneous." 

Let us now again refer to Table IV., and contrast the effects 
of characteristic constituents, or combinations of manure, upon 
some of the most important of our agricultural crops ; which stand 
in relation to each other, in very different positions in our rotations. 

We may first premise, that owing to the great liability to 
disease in the leguminous crops, especially when groum aynii" 
nuously^ the final produce in their cases, was frequently much 
less than it promised to be in the earlier stages of growth. The 
results relating to beans, are in all cases the averages of several 
seasons ; and those in regard to clover, apply to the years 1849, 
1851, and 1852, wheat being the crop in the intermediate year ; 
and, as will readily be understood, the produce in the last two 
years, was both meagre and irregular as compared with that on 
the same plots in 1849, in which season the crop was very large. 
For the sake of comparison with the other crops, the clover is 
given as before stated in about the same state of dryness as ihe 
beans and grain ; that is to say, the figures in the Table represent 
the dry svJhstwnce, plus one-sixth of its weight of water. 

It will be observed, that with a manure of potass alone, the 



Agricultural Chemistry. 65 

two legnminous crops (beans and clover) give a very considerable 
aiverage increase ; thongh in individual years, it was very mnch 
greater than this Table of averages merely, would indicate. 

A mixture o{ potass, soda, and magnesia^ ga^o with wheat a 
small average increase ; with the other cereal, barley, there was, 
taking the average, a slight deficiency. But, with beans and 
clover, the supply of Alkalies again produced a considerable 
increase. 

SuperphospJiaie of lime has given with the cereals a small ave- 
rage increase ; with beans on the average there was a deficiency ; 
with clover a very small increase ; but with turnips, an average 
increase of total produce, of more than 7 tons. 

When to the superphosphaie of lime, potass is added, we get 
scarcely any increase with wheat ; a notable increase witji beans, 
though less than when the potass is used alone ; a very consider- 
able increase with clover; and with turnips, a considerable 
though less amount of average increase than when the super- 
phosphate of lime was used without the potass. 

Nitrate of soda gives with both the cereals, a very considerable 
increase. 

Ammonia-soMs also gave with both the cereals a large amount 
of increase ; and in the case of wheat a large increase was ob- 
tained in other soils of very different quality, as well as at 
Boihamsted. These ammonia-salts, however, which with the 
comparatively speaking deficiently nitrogenised cereals, give 
SQch a large amount of increase-^with the highly nitrogenous 
luminous crops, give in the case of the beans an average of 
only 14 lbs. of increase, and with the clover an actual deficiency. 
And with turnips, we have with ammonia-salts alone, oiily a few 
bondredweights of increase, instead of more than as many tons 
with snperphosphate of lime. 

The mixture of superphosphate of lime, with a large amount 
of ammonia-salts, gives a greater increase with both wheat and 
barley, than the ammoniacal salts alone. With the leguminous 
crops, the mixture of ammonia-salts and superphosphate of lime, 
yields scarcely any beneficial result ; indeed wit^ clover there was 
on the average a deficiency. It should be stated, however, that 
owing to the even injurious effects observed on the use of much 
ammonia-salt with the leguminous crops, the quantities employed 
per acre in the cases in question, were much less than with the 
cereals. In the turnip experiments, also, much less of these 
BaltB was found to be appropriate than in the case of the grain 
crops, and less therefore was employed. But, although when 
QBed alone, the ammonia salts gave no appreciable result 
with turnips, yet, when mixed with superphosphate of lime, they 
increased the efficacy of the latter manure. Thus, we have with 

B 



66 Aijricultural Cftemistry. 

the mixture 8 j tone of increase of gross produce of tnrnips, 
instead of only about 7 tons with the superphosphate of lime alone. 

The addition o{ potass, to a mixture of superphosphate of lime 
and ammonia-salts, gives a still further increase in the case of 
wheat. With the leguminous crops we have now again a striking 
increase, and with turnips also a considerable one. 

Lastly, — a mixture of ammonia-salts, and a liberal mineral 
manure, containing superphosphate of lime, potass, soda, and 
magnesia, gives a very large increase with every one of the crops 
enumerated. The efficiency of a full supply of minerals, is seen 
to be very marked even with the cereals, when mixed with a 
large amount of the ammonia-salts ; that is to say, when these crops 
(the cereals) are supplied, at the same time, with such an amount 
otavailahle nitrogen in the soily as, when used alone, gives a produce 
nearly equal to that which would usually have been obtained in the 
ordinary course of farming. Themixtureof ammonia-salts with mi- 
nerals does not, however, with the leguminous crops, give obviously 
more increase than when the minerals, and especially the cUkulies, 
are used alone^ And again, the result upon the turnips^ of this 
full manuring — supplying as it does every important constituent 
except carbon — shows that which we have elsewhere so promi- 
nently maintained, namely, that however much the healthy growth 
of that crop may be increased by the direct use of minerdly and 
especially o{ phosphatic manures, yet that for the production of a 
full crop, a supply loithinthe soil of matter for organic formaiions 
is quite essential. And, had we farther extended the plan of our 
Table, so as to show the effect of manures containing carbon, it 
would have been seen, as we have frequently pointed out, that 
such a supply yielded a more characteristic result with the roots 
than with the other crops enumerated ; next in order to these 
would probably come the leguminous crops ; and lastly the cereals, 
which are benefited least of all by manures supplying carbon. 

A study of this condensed summary of a vast collection of 
facts will be found highly instructive. As a main result it may 
be stated, that the average increase by mineral constituents alone 
is with the cereals less than 200 lbs., whilst with the legu- 
minous crops, even though including so many cases of really 
deficient crop arising from disease, it is four times as much. On 
the other hand, the cereal grains give an average of from 1800 
to 2000 lbs. of increase with nitrogenous manure alone; whilst 
by the same manure there was on the average, with the legu- 
minous crops, not any increase at all. Then again, with turnips, 
we have by mineral manures alone, an average increase of gross 
produce of about 6^ tons, but with ammonia-salts alone, of only 
as many hundredweights. But, if we still more carefully compare 
the action of the several individual constituents of manure, witb 



Agricultural Chemistry. 67 

that of their several combinations, upon each of the different 
crops, and then again crop with crop, we cannot fail to see, that the 
general result is entirely inconsistent with that which the collec- 
tive analysis either of the crops or of their ashes would have led 
us to, had this alone been our guide. Finally, in prominent 
outline, the result is seen to be, that for the production of 
increased growth, nitrogenous manures had the most characteristic 
effect upon the cereals; potass on the leguminous crops; and 
phosphaies on turnips. 

There is another very important point connected with 
manuring^ in relation to which we must here adduce some 
experimental evidence, and a few observations. The subject, 
however, is one which, both from its extent and import^ce, 
demands that a separate paper should be devoted to its elucida- 
tion ; we therefore the less regret the very cursory manner in 
which we are now obliged to notice it. 

The point to which we refer, is the constantly observed fact 
throughout our experiments, that, although an increased produc- 
tion of the cereal grains (the main saleable produce, and, as it 
were, the final product to which all farming operations tend) is 
only attainable in agriculturally adequate amount, by the accu- 
mulation of available nitrogen vrithin the soil itself, — yet, in no 
case have we recovered in the increase of crop obtained, as much 
nitn^n as was supplied to the soil in manure. Now, if it be 
proved, that increase of the cereal grains in agricultural quantity, 
is essentially connected with the supply to the soil of much more 
nitrogen than is recoverable in the increased produce obtained, 
it will be obvious, that we have here a fact, which must funda- 
mentally affect the views we entertain as to the principles in- 
volved, not only in direct manuring, but in those other main 
features of agricultural practice, which are had recourse to with 
the same result. 

In relation to this subject, we have in our various papers, pro- 
minently called attention to several of the main facts which our 
experiments have brought to light. Thus, we have shovni that, 
ftfter supplying to the soil twice or thrice as much nitrogen as 
was obtained in the increase yielded, there was in the succeeding 
year, either no increase whatever due to the nitrogen not recovered 
in the year of its application, or that such increase in the second 
year, if any, was not only extremely small, but that it occurred 
only when the application of the previous year, had been obviously 
very excessive in relation to the climatic or other circumstances 
of growth of the particular season. We have also called especial 
attention to the fact, that the increase produced by a given 
ftmount of nitrogenous supply is very variable, according to the 

 2 



68 AgricvUurdl Cliemistry. 

variations of season, and of other coincident condifcions of the 
growth and maturation of the crop. 

But, Baron Liebig in his criticisms equally ignores oar fects, 
our observations, and oar conclusions regarding them ! With a 
view of maintaining that the increase of produce obtained was 
not proportional to the supply of ammonia by manure, and con- 
sequently that the results of our own experiments demonstrated 
the contrary of that which he alleges we have concladed firom 
them, Baron Liebig compares the increase by a given amount of 
ammonia in differerd seasonSy without any reference either to the 
varying character of tJtose seasons, or to the fact, that in recording 
the experiments of which he treats, we had ourselves called 
2>articalar attention both to the actual variations^ and to their inflw' 
ence upon the results in question. Thus he selects for his purpose, 
results obtained in the several seasons of 1844, 1845, and 1846 ; 
and shows that in the last (1846), the increase obtained from a 
given amount of ammonia-salts in manure, was once and a half 
or twice as great as in the other cases. In reference to this 
very point we had said : — 

'' It should be remembered, howeTer, that as the season of 1846 was more 
than usually favourable to the production of com, any calculations founded 
upon the results of that year rmght lead to an over-estimate of what the amr- 
monxa lootdd ptvduce in an average of years,^* — Jour, Hay, Ayr, Soc. JEng,^ 
-vol. Tiii. part i. p. 247. 

Again, speaking of the total amount of ammoniacal salts 
added to one of our plots (10a), in six years, he says : — 

" But as the whole 1960 lbs. was not added in one year, but in portions 
durinfj^ six years, the soil became each year richer in them than it waa in the 
preceding. There remained a residue from the previous year, which waa 
annually increased by the portion newly added." — Prineq)les, p. 95. 

He then, in direct contradiction to the evidence of our experi- 
ments, goes on to deduct from the amount of nitrogen supplied 
to the soil in each year, that amount which he supposes was con- 
tained in the increase of crop obtained by it ; he assumes that 
the remainder accumulates from year to year, as a residue in the 
soil, the amount of which residue, taken together with that of 
the salt newly added, is to be considered as the amount of 
ammonia-salts yielding the increase of any particular year. In 
this way, by bringing forward from year to year an assumed 
efficient residue, which our experiments prove did not exist, he 
calculates the increase of produce in the sixth year as due to 
1592 lbs. of ammonia-salts! — ^though 400 lbs. only was the 
amount added as manure in that year. In this way it is, he 
arrives at the conclusion, that the produce for a given amount of 
nitrogen steadily diminished ! He says : — 

^^But it it and rmnains undeniably certain f that the proportion of ammonite* 



i 
I 

\ 

i 



AgiicuUural Chemistry, 69 

eal salts in the soil, whatever might he its exact value, must have increased 
from jear to jear, hecause ammoniacal salts (sulphate of ammonia and sal- 
ammoniac) are not volatile, and, consequently , the unoonsumed portion, or 
exce$$, mu9t have renuained in the soil. Thih being assumed as a fact which 
cannot be disputed, these numhers establish the truth, already demonstrated 
by the earlier experiments, that the produce did not increase in proportion 
to the increased proportion of nitrogen present in the soil; but that, with the 
exception of the year 1848, the produce for the same amoimt of nitrogen 
steaaify diminished," — Principles, p. 97. 

It 18 after the wholesale ignoriDg of our recorded facts, state- 
ments, and conclusions, which these quotations imply, and after 
such reasoning upon the pure assumptions taken in their stead 
as we have pointed out above, that Baron Liebig, using the word 
^^proportional " in the exact numerical sense (which he well knows 
is entirely inconsistent with all our evidence and reasonings 
on this question), sums up his criticism by saying : — 

** Mr. Lawes has disproved what he intended to provCy namely, that the 
exoesB of produce in this case is proportional to the quantity of ammonia 
present in the soil ; — that i?, he has proved that a single, double, or treble 
supply of ammonia does not give a single^ double, or treble evcess of produce ; 
but that this excess is a constant quantity." — Principles, p. 135. 

Already, however, in Germany, America, and this country. 
Baron Liebig's treatment of this question has been prominently 
commented upon. And thus it is, that he has been obliged to 
recur to the facts and conclusions involved in this part of the 
subject. At the recent meeting of the British Association at 
Glasgow he undertook to deal with this question ; and as the 
line of argument he then adopted was substantially that which 
he had alre-ady published in Germany in reply to the admirable 
strictures on his ' Principles * by Professor Wolff,* we shall, for 
convenience, refer to the translation of his own reply, made and 
published at his own (Baron Liebig's) request in America.f 

In discussing this question, we need not for a moment enter- 
tain as an objection against observed collateral facts, Baron 
liebig's argument, that if there be a loss of nitrogen in the 
growth of increased produce, there must necessarily be the same 
relation between the normal supplies of nitrogen and the amount 
assimilated under their influence on our unmanured plot. It 
must then be distinctly borne in mind, that it is of actually 
observed facts, in relation not to the growth of produce alone, but 
of an increased amount of produce by means of an accumulation 
of nitrogen within the soil, that we have now more particularly to 
speak. We may, however, say in passing, that we have frequently 
called attention to facts regarding the amount of constituents 
liarvested over a given area of unmanured or equally manured 

* Zeitschrift fUr Deutsche Landwlrthe, 4en Heft. 

t The Ooontiy Gentleman. Albany, N.T., October 11, 1865, et seq. 



70 AgricuUurdl Chemistry. 

land, In the cereals and legaminous crops respectively, ^hicli are 
calculated to give at least a direction to our conclusions, in refer- 
ence to the assimilation of nitrogen in the case of an tminannred 
cereal plot. Thus, the striking fact appears, that under similar 
unmanured or mineral-manured conditions, the produce of nitro- 
gen per acre, may be twice and a half or thrice as great in one 
and the same season, with the leguminous, as with the cereal crop. 
This relation, therefore, between the amount of nitrogen assimi- 
lated under given circumstances in the leguminous crop, as com- 
pared with the cereal, is strikingly similar to that which is found 
between the nitrogen of manure and that in the increased produce 
of the cereal obtained by its use. 

Baron Liebig further alleges against our conclusions, that we 
have no evidence that the unrecovered nitrogen did not remain 
in the soil for the use of the future crops ; that we should have 
employed very much smaller amounts of ammonia-salts, to prove 
that the smaller did not give an equal increase of produce with 
the larger, as well as to ascertain the minimum amount of am- 
moniar-salts required to produce a maximum effect ; and, inrther, 
that the assumption that 5 lbs. of ammonia is required to produce 
a bushel of increase is no expression of a natural relation between 
manure and crops. We shall examine these several allegations. 

Firstly, then, as to the assertion that we have no evidence that 
the unrecovered nitrogen of the manure did not remain in the 
soil for the succeeding crops. Not only had we sufficient evi- 
dence on this point, but Baron Liebig had himself, in our own 
recorded results, the proof of it in the degree in which we have 
ourselves maintained it. What we say is, that even when ammonia- 
salts are not used in greater excess than is adapted for a full 
average effect in any given season, still, probably, only from one- 
third to one-half of the nitrogen so supplied, will be recovered in 
the increase obtained in the year of the application ; that this 
unrecovered nitrogen will yield little or no increase in the suc- 
ceeding year ; that if, under these circumstances, ammonia be 
again added, we shall, other conditions being equal, again get a 
large increase of produce ; and further, that if more ammonia 
have been employed than is suited to give a fair increase of crop 
on the average of seasons, even then the effect of the residue in 
the succeeding year will be, comparatively speaking, very trifling. 
The registry of facts in Table V. will illustrate the above state- 
ments. 

We could multiply instances of this kind illustrating the point 
in question ; but those here given are sufficient to prove ihefauct^ — 
that a moderate supply of ammonia-salts to the wheat crop, did 
not leave any efficient residue for the succeeding season. And 
such a result, we maintain, is entirely in accordance with the 



Agricultural Cliemisiry, 



71 



experience of practical farming in the use of guano, and other 
nitrogenous manures, for the increased production of the cereal 
grains. 

Tablb V. — Showing the influence upon the Whe.it Crop,in the second season, 
of Nitrogen supplied in Manure (but not recovered in increase) in the pre- 
ceding season. 



VMM. 


Seasona. 


Ammonia- 
salta employed. 


With or 
witUout Minerals. 


Increase of 

Total Produce 

(Corn and Straw 

per acre). 


lOa. 1 

10*. / 

8*. 1 

6a. 1 

6*. ^ 


1845 
1846 

1845 
1846 

1R47 
1848 

1861 
1862 

1861 
1862 


Ibo, 
336 

224 

3-^6 
none 

400 
none 

600 
none 

600 
none 


none 
none 

none 
none 

minerals 
do. 

minerals 
do. 

minerals 
do. 


lbs. 
^,0113 
1,374 

2,093 
49 (less) 

2,715 
82 

8,477 
468 

8,778 
624 



Secondly, Baron Liebig says — 

" If it had accidentally occurred to Mr. Lawes to ntanure hid field with 
4,5, or 6 cwt. of ammonia-salts, instead of with 3^ cwt., and if in those cases 
the yield was not increased (as we may with certainty assume would happen), 
then be mifht with the same justice assert that the loss of ammonia is 
6, 8, or 10 lbs. for every bushel of increased yield. 

"Or if Mr. Lawes had applied ammonia-salts at the rate of 2 or 1 cwt., 
instead of 3^ cwt. the acre, and then, after previous manuring with dissolved 
bonea and silicate of potash, (whose action he has not tiucen at all into 
tccoont), had harvested the same increase of 8 bushels ; his conclusion that 
the soil sufliBrs a loss of ammonia, would doubtless have been vastly modified, 
tie has made the loss and not found it.'* — The Country Gentleman, Nov. 1, 
1865. 

And again — 

" It never seems to have occurred to Mr. Lawes to determine the minimum 
of ammonia which was effective upon his field in producing maximum crops." 
— Ibid, 

Doubtless it will be highly satisfactory to Baron Liebig to 
learn, that it has occurred to us to supply almost identically 
all the cases here demanded. Thus, instead of using only 
400 lbs. of ammonia-salts, which is rather more than on the 
average of seasons is adapted to our soil, we have, over a series 
of years, employed 600 lbs. and 800 lbs. of these salts ; and the 
result has been exactly the reverse of what Baron Liebig says 
" ice may with certainty assicwe would happen'^ That is to say, 



^ 



72 Agricultural Chemistry. 

the crop uxthooe cs^sea was very. c(msiderably Thoiigli,a8 

might be expected, in a diminishisg numerical proportion to the 
excessive amount of ammonia now added. Then again, we have 
used, through the same series of years, respectively 200 lbs. and 
100 lbs. of ammonia-salts, with, in each case, a full supply of solu- 
ble phosphates and alkalies ; so that we have here again supplied 
the exact conditions demanded; and also the means of determining 
the *' minimum " amount of ammonia which was effective in pro- 
ducing a maximum crop. Here, too, the results are precisely 
contrary to those which Baron Liebig has supposed they wonld 
be, and on the assumption of which he says, that then '^ his con- 
clusions that the soil suffers a loss of ammonia would doubtless 
have been vastly modified. He has made the loss, and not found 
it." ! 

The following is a summary statement of the results obtained 
by the use of these gradationary amounts of ammonia, over a 
period in each case of three years, namely, 1852—4 inclusive. 
And in order to show by the side of these results, about what 
amount of produce was obtained on the same soil by means 
which the practical farmer will be better able to judge of, we also 
give the average produce by farm-yard manure during the same 
seasons ; and, by the comparison here afforded, it will be seen, 
that some of the supplied amounts of ammonia were very far in 
excess of what was required to give a produce equal to that by 
the annual supply of farm-yard manure. 

Tablb VI. — Showing the effects upon the Wheat Crop of gTadationary 

amountA of Ammonia in Manure. 







Total Inoieaae 






per acre 






(Ooxn and Straw). 




Iba. 


Average of 8 years 


with minerals and 100 lbs. ammonia-salts . 


760 


Do. do. 


do. 200 do. 


1.676 


Do. do. 


do. 400 do. 


2,916 


Do. do. 


do. 600 do. 


3,641 


Do. do. 


do. 800 do. 


4,655 


Do, do. 


farm-yard manore ... , 


8,022 



Here it is seen that the 100 lbs., the 200 lbs., and the 400 lbs. 
of ammonia*-salts, gave a gross increase of produce (com and 
straw together), almost identically proportionate to the amount 
of ammonia in the manure. As we have already said, how- 
ever, the largest of these amounts (400 lbs.) is somewhat more 
than on the average of seasons will yield the most favourable 
result ; and if it be piuch exceeded, the proportion of straw 



Agricultural Chemisiiy. 73 

to com in the gross produce obtained will be much increased. 
It should be further added, too, as some qualification of the exact 
figures of the Table, that since the three seasons over which our 
average extends, include one at least which was unusually favour- 
able to the production of com, the result by even the 400 lbs. 
of ammonia-salts, as here recorded, will be rather better than 
would be obtained over a more extended period of time. There 
was, however, a still further increase of produce when more 
ammonia was employed; though, as already stated, the ratio 
of increase diminished the more rapidly the greater the excess 
of ammonia added in the manure. 

Upon the whole, then, the result strikingly stands out, that 
we obtained a considerably greater amount of produce by the 
use of TTiTich larger amounts of ammonia than those which Baron 
liebig has pronounced to be ex^essive^ and to the use of which 
he attributes the conclusion which he assumes to be so erroneous. 
It is farther strikingly obvious, that there was a very general uni- 
formity in the proportion of increase obtained for a given amount 
of ammonia supplied, whether 400, 200, or 100 lbs. of its salts 
were added to the soil. Hence it follows, that if there were a 
loss of nitrogen when 400 lbs. of ammonia-salts were used, there 
must have been very nearly a proportionate amount of loss when 
the minimum quantity was employed ; and consequently that the 
loss observed when the 400 lbs. was used could not be due simply 
to the supply of more nitrogen than was necessary for a maximum 
of produce, as maintained by Baron Liebig. In fact, we have 
found the hss^ and not made it ! 
Again, Baron Liebig says : — 

''The number 5, for the amount of ammonia, and the quantity 1 bushel for 
the incTeaeedyield, are not expressions for a natural relation between manure 
and crops. Hhe first does not express the weight of ammonia necessary to 
produce a maximum of increase, equal to one, and ascertained by a series of 
obaerratbns, but is a mere stroke of fancy." — The Country Gentleman, 

We will first show, by quotation from our papers, whether 
we have assumed '' the number 5 for the amount of ammonia, 
and the quantity 1 bushel for the increased yield," as an uncon" 
ditional and undeviaJting relation ; or whether these numbers are 
not given simply as a practical average of our experiments, ad- 
mitting deviations on either side, according to variations of 
aeaaon and other circumstances. Secondly, we will show whether 
or not that which we have assumed, is " ascertained by a series of 
observations," or whether it is " a mere stroke of fancy." In 
regard to the first of these points, we had said : — 

''I am inclined to think that, for practical purposes, we may assume 5 lbs. 
of ammonia to be required for the production of every bushel of wheat beyond 



74 Agricultural Chemistry. 

the natural yield of the soil and seaaon ; at anj rate, it will he naefiil to 
rememher this as the amount until future experiments shall furnish further 
information on the subject/' — Jour. Roy, Ag, Soc, Eng,^ vol. yilL, part L 
p. 246. 

'' We may here observe that the production of straw, as well as that of grain, 
would seem to be intimately connected with the expenditure of nitrogen de- 
rived through the roots of the plant, and had we time to consider the question 
more fully on this occasion, we should not have dwelt so exclusively on 
the production of corn alone as we have done. We may, however, remark, 
that the production of a heavy crop of straw in a wet season is probably, from 
the cause alluded to, a very dearly purchased produce.'' — VoL xii., part L 
p. 27. 

'' In our paper upon the growth of wheat, published in the Journal of the 
Royal Agricultural Society in 1647, we have attempted an estimate of the 
probable amount of nitrogen n^uired to obtain a g^ven amount of it in the 
increased produce. We there provisionally assumed that 5 Ibe. of ammonia 
were required to produce an increase of one bushel of corn and its equivalent 
of straw. We do not intend to enter fully into the question of the accuracy of 
this estimate on the present occasion, but we may observe in passinsr, that 
among the plots the history of which we have given in the foregoing psgea 
down to the last harvest, there is not one, even under the best conditions as to 
artificial mineral supply, where the ammonia, on the average of seaaons, has 
given an increase equal to that supposed in our estimate 

** Without further inquiring then, into the correctness of our estimate,it would 
seem that a loss of this kind during the growth of the plant is a fact which ia 
sufficiently substantiated, at once by the practical experience of the farmer, and 
by experiments of an independent kind relating to it. And. let it once be recofr- 
ui8ed,in agricultural science, that there is a definite expenditure or consumption 
of the nitrogenous bodies derived through the roots, connected with the fixation 
and elaboration of certain constituents ef plants, and that this b greater or lef^a 
according to the sources or the exact composition or state of elaboration of tiie 
products, and an important step will be gained towards a clearer conception 
of the principles involved in the alternation in a course of cropping, of plants 
of varying products and habits of growth." — Vol. xii., part i. pp. 31^ 32. 

We will next show whether or not that which we have assumed 
regarding the excess of nitrogen required in manure over that 
obtained in the increase of the cereals grown by it, was " a mere 
stroke of fancy," or whether it was " ascertained by a series of 
observations." On this subject we will bring one quotation 
from our former papers, and we will then adduce a summary of 
an immense mass of experimental evidence on the point in ques- 
tion. We say : — 

''Thus, among from two to three hundred experiments with ammoniacal 
manures, we have in no single instance recovered in the increase the amount 
of nitrogen provided in the manure ; and this fact is perfectly consistent with 
the amounts of produce found, in the experience of the farmer, to be obtained 
by the use of Peruvian guano and other nitrogenous manures." — Jmtr, Ray, 
Agr. Soc, Eng., vol. xii., part i. p. 29. 

In the following Table (VII.) is given a summary of the 
amount of nitrogen recovered in the increased produce, for every 
hundred parts of it supplied in manure, in the cases both of 
barley and of wheat. It will be seen, that we have here the 



Agricultural Chemisiry. 



75 



resnlte obtained ander eight different conditions as regards the 
nature of the nitrogenous manure, its amount, or the circum- 
stances under which it was employed,yiz., whether with or without 
the addition of mineral manures. The number of cases brought 
under calculation, including both wheat and barley, amounts to 
nearly 300 ; and the number of years over which the experiments 
extended, was nine in the case of wheat, and three in the case of 
barley. T}ie minor questions as to the influence of individual 
seasons, the varying proportions of com and straw, the slightly 
var}'ing percentage of nitrogen due to the combined influences 
of season and manure, and other points, it would, of course, 
be impossible to treat of, in the mere outline which we are now 
professing to give. With regard, however, to the varying per- 
centage of nitrogen in the produce according to the amount of it 
in manure — a point to which Baron Liebig alludes — we may 
simply say, that it in no way materially affects the general result 
obtained. We may add, that the percentages of nitrogen in corn 
and straw respectively, employed in the calculations, are in most 
cases the results of direct determinations made upon mixed 
samples of the produce (grain and straw separately), of the 
several plots in each year, the average of which go to form a 
single result in the Table. 

Table VII. 

Summary — Nitrogen in total increase (Com and Straw) for 100 in Manure. 

Crops— Wheat and Barley. 



General Description of Mannres. 



1. Ammonia-salts (standard amount) alone 

2. Nitrate of soda ( do. do. ) alone 

3. Ammonia-salts ( do. do. ) with minerals... 

do. ) do. 



i. or rape-cake J ^ 



Wheat. 



5. Ammonia-salts (less than standard) do. 

6. Mitiate of soda ( do. do. ) alone 

7. Ammonia-salts (morethan standard) with minerals 

Means 



81-9 
29-3 
42 6 

38-3 



53-4 
62-2 

34-3 
37-2 



Barley. 



39-9 



43-4 
28-4 
48-1 

36-6 



60-6 
42-4 



431 



The results here stated may surely be considered as '^ ascer- 
tained by a series of observations." We have, first, the amount 
of nitrogen recovered in the increase of wheat and barley, when 
what is termed a '^ standard amount " of nitrogen alone, is em- 
ployed ; that is to say, such an amount as experience shows will 
yield a pretty fall, but rather too heavy a crop to bear the 



76 AgiicuUural Chemistry. 

ay^<age of seasons. We have this amount supplied both in the 
form of ammonia-salts, and in that of nitrate of soda. We have 
it also with the admixture of minerals ; and again when, besides 
minerals, the same amount of nitrogen is supplied indifferently 
in the form of rape-cake alone, or a mixture of rape-cake and 
ammonia-salts. We have next, in Series 5 and 6, the amount of 
nitrogen recovered, when less than the standard amount of nitro- 
gen was employed. And lastly Series 7 and 8, when more than 
the standard amount of nitrogen was used. 

Now, since season has a very great effect upon the amount and 
description of the increase obtained by nitrogenous manures, ftnd as 
the whole of these series do not apply equally to the sameyears,it is 
obvious that niceties of variation cannot be discussed upon such a 
summary statement of results as is here given. The general fact is 
clear, however, that the proportion of the supplied nitrogen not 
recovered in the increase of crop, is, in all cases, very large. The 
proportion of loss is greater when the standard amount of nitro- 
gen is used alone, than when a liberal supply of minerals is also 
added. But it is seen, that even when only the standard amount 
of nitrogen is used (an amount which does not yield more in- 
crease than should be obtained under high farming on the land 
in question), and when to this is added a liberal supply of 
mineral constituents, still there is little more than 40 per cent, 
of the supplied nitrogen recovered in the increased produce of 
corn and straw which is obtained. When, again, with the 
minerals, less than the standard amount of ammonia is employed, 
that is, less than is adequate to give an a/mount of crop equal to thai 
produced Inj good fammvg^ — we have, even in that case — a case 
which of course in practice could not he followed — little more than 
50 per cent, of the supplied nitrogen recovered in the increase of 
crop. But when, with the mineral constituents, we add mcrre 
than the standard amount of nitrogen, though not more than gave 
a still further increment of increase^ we have little more than one- 
third of the nitrogen of the manure returned in the increase. 

It is seen, that with both wheat and barley, a large amount; 
of nitrogen alone, applied as nitrate of soda, gives a worse result 
than a large amount of salts of ammonia alone. The nitrogen 
applied as rapen^ke gave, in the case of wheat, nearly an equal 
result with that in ammonia-salts ; when used with barley, it 
gave considerably less return in its increase than when applied in 
the latter form ; but the amount of rape-cake employed, was 
obviously far too great for the favourable maturing of the barley 
in the average of seasons. 

As a final average it is seen that we have, including all these 
cases and extending over so many years, in the case of wheat, 
only 39*9 per cent., and in that of barley only 43*1 per cent, of 



4^gricuUural Chemistry^ 77 

the iiitr<^en of the manure recovered in the increase of crop ! — 
and certainly the near approximation in the averages of the two 
crops is not a little striking; especially when we remember, that in 
the case of the barley there were no instances of more than standard 
amount of nitrogen used, which would obviously have brought 
down its final average nearer to that of the wheat. 

Now, the final average here obtained in the case of wheats 
would represent exactly 5^ lbs. of ammonia for each bushel of 
grain (with its equivalent of straw), obtained by its use, assuming 
average proportions of com to straw, and of nitrogen in both : 
and, again, by the same method of calculation, the return of rather 
more than 40 per cent, of nitrogen, the result where the standard 
amount of ammonia with minerals was used, would be almost 
identiccklly equivalent to 5 lbs of ammonia in manure for every 
bushel of corn, and its equivalent of straw, obtained as increase 
of crop ! 

So much, then, for the indications of some hundreds of direct 
experiments on this subject. But we further unhesitatingly 
maintain, that the general result here arrived at, agrees very closely 
indeed with that of common experience in the use of guano 
and other nitrogenous manures for the increased growth of grain. 
Consistently with the object of this paper, which is simply to 
meet the objections of Baron Liebig to our facts and conclu- 
sions, and to adduce, in the form of condensed summaries of our 
experiments, such evidence as shall serve to establish the facts 
and conclusions thus disputed, it would be out of place, even did 
our space permit it, to enter into any detailed consideration of 
what may be the scientific explanation of the practical loss of 
nitrogen, which as a simple fa/it we have just illustrated. Hoping, 
however, to recur to this subject before long, we may neverthe- 
less, in passing, state, that various experimenters have recorded 
an evolution of nitrogen fix)m the leaves of growing plants, 
beyond that which they thought they could attribute to the 
atmosphere with which their plants had been supplied ; but as 
observations of this kind have not established a clear distinction 
between the leguminous and the cereal plants of our rotations in 
this respect, further evidence is of course necessary, before we 
shonld be justified in confidently attributing the phenomenon in 
question, to the functional actions which have been supposed to 
be the source of the evolution of nitrogen firom the leaves of 
plants, observed in the experiments alluded to. The only expla- 
nation of this practically observed loss, which has been suggested 
M sptidaL to the cereals^ is that proposed by Mr. Way ; namely, 
tihat the silica required by these plants, is taken up as a silicate, of 
which ammonia is a base; and that this alkali, or its constituents, 
is evolved upon the fixation of the silica by the plant. Professor 



78 Agricultural Chemistry^ 

Wolff has to a great extent adopted this view ; and has addaoed 
various circumstances connected with the development of these 
plants, as corroborative of its probability. Baron Liebig has, on 
the other hand, energetically repudiated the explanation offered 
by Mr. Way ; founding his objections on the fact, that water 
containing ammonia or its salts dissolves less of the alkaline 
silicates than does pure water itself. Experiments of this kind, 
made upon chemical compounds oid of the soU, cannot be con- 
sidered satisfactory as the ground of conclusions as to what 
would happen under the complicated conditions of cultivated 
soils. We have, however, found, that water containing salts of 
ammonia dissolved less silica than pure water, when percolated 
through a given bulk of soil. But the question may, after all, 
not so much depend upon the amount of the silica which will be 
dissolved in the soil, as upon the state of chemical combination 
from which it is most easily assimilated by the plant. 

It has been partly with a view to aiding the solution of the 
question of the varying amount and sources of the nitrogen assi- 
milated by the different plants of our rotations, that we have, for 
a series of years, conducted investigations on the amount of water 
passing through different plants, under equal and varied condi- 
tions of growth, in relation to the quantitative fixation in them 
of their several constituents. The results of these investigations, 
as we have elsewhere pointed out, have an interesting bearing 
upon the phenomena we have been discussing. But so important 
has it appeared to us, to clear up many open questions which 
suggest themselves, that not long ago we induced a promising 
and accomplished young chemist from the laboratory of Professor 
Bunsen (Dr. August Pauli), to devote himself for two years to 
this subject, in the laboratory at Rothamsted. Unfortunately, his 
death, almost as soon as he had commenced his labours, pre- 
vented the further prosecution of the exact path of research then 
proposed ; though we still hope that investigations which we 
have for some time had in progress, and to which we shall now 
direct more close attention, will enable us to record before long, 
farther advance in our inquiry. 

But there are means adopted by the farmer of increasing 
the growth of grain, without either the artificial supply of 
nitrogen to the soil, or the intervention of a fallow crop. These 
are, hare fallow and the mechanicdl operatiofis of the fa/rm. Now, 
as Baron Liebig has modi6ed his views on the efficiency of these 
means, in his '' Principles " just published, we must take the 
statement of his views as given in the third and fourth editions 
of his main work, to show what, until lately, he advocated on 
this question. In these editions he gave a distinct and separate 



Agricultural Chemistrtj. 79 

cliapter on &llow and the mechanical operations of the farm, in 
which is found all but the first of the following seutences ; this 
one immediately preceding that special chapter : — 

'* From the preceding part of thia chapter it will be seen that fallow is that 
period of culture when the land is exposed to progressive disintegration by 
the action of the weather, /or the purpose of liberating a certain quantity of 
alkalies and silica to be absorbed by future plants, 

'^The careful and frequent working of fallow-land will accelerate and 
increase its disintegration : for the purposes of culture it is quite the same 
whether the land be covered with weeds, or with a plant which does not 
extract the potash from the soiiJ" —4th Edition, p. 127. 

Speaking of the mechanical operations of the farm, he says : — 

" Their action consists in accelerating the weathering or disintegration of 
the mil, and thus offers to a new generation of plants their necessary mineral 
constituents in a form fit for reception" — ith Edition, p. 130, 131. 

** We renew the sunace of the soil and endeavour to make every particle 
of it accessible to the action oi carbonic add and oxygen. Thus we procure a 
new provision of soluble mineral substances which are indispensable for the 
n()ur»hment and luxuriance of a new generation of plants. —4^ Edition^ 
p. 132. 

And again : — 

"Fallow, in its most extended sense, means that period of culture during 
"which a soil is exposed to the action of the weather, for the purpose of en- 
riching it in certain soluble ingredieats. In a more confined sense, the time 
of fallow may be limited to the intervals in the cultivation of cereal plants ; 
for a magazine of soluble silicates and of alkalies is an essential condition to 
the existence of such plants." — ith Edition^ p. 132, 133. 

''The mechanical operations of the farm, fallow, the application of lime, 
and the burning of clay, unite in elucidating the same scienti6c principle. 
Tketf are the means of accelerating the disintegration of the alkaline silicates 
qfaluminaj and of supplying to plants their necessary constituents at the 
commencement qfa neto vegetation^* — ith Edition, p. 136. 

Now, fallow would generally be applicable to land after its 
agricultural exhaustion by the growth of a series of crops, and as 
A preparation for the growth of a succeeding crop of grain — and 
we maintain, that in 99 out of 100 such cases, in ordinary culti- 
vated lands, mineral manures would not adequately raise the pro- 
duce, whilst the application of ammonia salts or nitrate of soda 
would certainly do so ; — we cannot imagine, therefore, that the in- 
crease in produce in such a soil by fallow, can be measurable by 
the amount of mineral constituents liberated by the chemical 
action of the atmosphere on the soil. We fully grant, indeed, 
that such action — such liberation of mineral constituents — does 
take place during fallow ; but we maintain, that there would be 
no adequate increase of produce, unless at the same time there 
were a condensation of available nitrogen from atmospheric 
sources within the soil itself, and that it is by the amount of this 
accumulation of available atmospheric food of plants within the soil^ 
rather than by the amount of liberated soil-proper constituents, 
that the increased produce of grain will be measurable. 



80 Agricultural Chemistry, 

It should be mentioned, that in the fourth and last edition of 
Baron Liebig's main work, in the chapter entirely devoted to an 
explanation of the beneficial effects of fallow and the mechanical 
operations of the farm, he does not say one single word in 
reference to the accumulation by these means, of available 
atmospheric food — nitrogen — within the soil itself; but only of 
the greater supplies of the mineral or soil-proper constituents, 
which are thereby rendered soluble and available for the plants. 
We have, on more than one occasion, called attention to the 
former influences ; and also to the fact, that a study of the pro- 
perties of soils in relation to the accumulation of the atmospheric 
food of plants, promised to be of more value to agriculture, than 
that of the mere determination of their percentage composition 
in the mineral food of plants ; and, to the opinion that this is a 
field of inquiry highly deserving of the attention of the agricul- 
tural chemist, we are happy to have now the sanction of Baron 
Liebig himself. Thus he now says : — 

" Fallow is the time during which this weathering takes place. During 
fallow, carhonic acid and ammonia are convened to the soil by the rain and 
the air : the ammonia remains in the soil, if substances be present in due 
proportion which deprive it of its volatility by combining with iu**— IVm- 
ciples, p. 26, prop. 26. 

And again : — 

'' But so to prepare the soil as to enable it to extract from the air, and the 
other sources offered to plants by nature, and to condense in its products a 
maximum of nitrogen, — ^this, indeed, is a problem worthy of scientific agri- 
culture.'* ! — Principles^ p. 106, 

Here again, then, in his 26th, as well as in his 14th proposi- 
tion, there is evidence that Baron Liebig's views have been 
strikingly " corrected and enlarged " ! This influence oi fallow 
is then we say, not that, there being within the soil a more 
liberal provision of the mineral food of plants, they, the planlSf 
are enabled to absorb more nitrogen from atmospheric sources ; 
but it is, so far as accumulation of nitrogen is concerned, that 
the soil itself has absorbed it from atmospheric sources ; without 
which condensation within the soil, of the atmospheric food of 
plants, no adequate increase of produce of grain would have been 
obtained, however great might have been the increased supply 
of the soUrproper or mineral food of the plants* 

We shall presently endeavour to trace the chemical statistics 
of an actual rotation of crops itself which will enable us to form 
a judgment, whether the facts which are thus elicited, taken in 
connection with those which have been indicated with regard to 
the action of manures on the individual crops, do not affi>rd xa 
some insight into the chemical principles upon which that main 
arm of agriculture, rotaiion^ is founded. Before, however, enter- 



Acp'icuUural Cliemistrif, 81 

ing upon a consideration of our own evidence and conclusions on 
this point, it may be well to give a very rapid review, of what 
may be called the natwral history of the various opinions which 
have of late years been entertained^ regarding the two most im-* 
portant and closely allied subjects, of manure and rotation. 

At the time of the appearance of Baron Liebig's first work in 
1840, the prevailing impression, which had received much con- 
firmation from the investigations of M. Boussingault, was, that 
nitrogen was one of the most important constituents of manure. 
Baron Liebig, in his first edition, also dwelt particularly on this 
point ; but at the same time, he drew much more special attention 
to the importance of the minerai constituents of plants than had 
hitherto been bestowed upon them. After the publication of 
Baron Liebig's first book, M. Boussingault published much more 
fully the results of his various agricultural investigations, and 
the conclusions to which he had arrived in regard to them. 

With respect to manures^ he (M. Boussingault) concluded that 
their relative value was determinable, more by the amount of 
nitrogen they contained, than by that of any other constituent. 
And in reference to the subject of rotcdion, after having given 
the chemical statistics of three separate courses, in which roots, 
leguminous crops, and cereals had been alternated with each 
other, and also of one with wheat grown two years in succession, 
after fallow and manure, he thus speaks in regard to the mutual 
relations of difierent crops : — 

" In the five years' rotation, it may be observed that there are two crops, 
the hoed crop and the forage crop, which yield substances to the ground that 
are both abundant in quantity and rich in azotised matter, and it is un- 

Sueetionable that these cro[ s act favourably on the cereals which succeed 
bem. But data are wanting for the appreciation of their specific utility to 
the general rotation." — JRur^ Economy j p. 488. 

And, again, in the next page, he says : — 

" When the relative value of different systems of rotation are discussed in 
the way we have done, we in fact estimate the value of the elementary matter 
derived from the atmosphere by an aggregate ot crops; but the procedure 
generally followed is silent when the question is to assign to each crop in 
particular the special share which it has had in the total profit." 

Now, Baron Liebig, after detailing the experiments of M. 
Boussingault — in the course of which he argues, that inasmuch 
M a larger amount of nitrogen was obtained in some of the later 
crops of the rotation, than in the earlier ones which immediately 
BQcceeded the application of the manure, it was obvious, that 
the nitrogen of the crops could not be due to the nitrogen of the 
^nanure which had been applied — says : — 

" Boassingault concludes that leguminous plants a A)n« possess the power of 
M^V^priating, as food, nitrogen from the air, and that other cultivated plants 
do not at all possess this pniperty. Hence the great importance which Bous- 

F 



82 AijricuUural Chemisfry. 

aingault ascribes to manures containing nitrogen, for, according to his view; 
the commercial value of a manure depends on its amount of nitrogen. But all 
these conclusions are thoroughly erroneous ; for, if they roere not so, it mutt 
follow that potass, lime, and silica plants, unless they belonged to the legu- 
minosuB, would not produce any nitrogen, unless they were supplied with 
manure containing that element.^ — 4th Edition, p. 207, 208. 

Baron Liebig goes on to maintain, that, owing to the method 
of experimenting adopted by M. Boussingault, he had obviously 
under-estimated the amount of nitrogen which he had supplied 
in the manure at the commencement of his rotations ; and that, 
in point of fact> he had added much more of that constituent to 
the soil, than he had taken off in his course of crops. And, on 
this point, he says : — 

'* Hence his erroneous conclusion, that the leguminosfe alone possess the 
power of condensing nitrogen from the air; and that it is necessary to furnish 
nitrogen to the gramineca, and to plants such as turnips and potatoes." — 
4th Edition, p. :^08, 200. 

Baron Liebig supports his general argument by reference to 
the produce of Hungary, Sicily, the vicinity of Naples, the 
valley of the Nile, the meadows of Holland, and of other locali- 
ties ; and he maintains, that the nitrogen in these cases must 
have been derived from the atmosphere, and not from manure. 
And, he asks : — 

<' Are the fields of Virginia, the fields of Hungary, our own cultivated 
plants, not ahle to receive it from the same sources as the wild-growing Tege- 
tation P Is the supply of nitrogen in animal excrements a matter of abtolute 
indifference: OB do we obtain in otjb fields ▲ an aktitt of the ooitstitu- 

SNTS OF THE BLOOD, ACTUALLT COBBEBPONDING TO THE SUPPLY OF AICICOKIA P 

" These questions are completely solved by the investigations of M. Boussin' 
gault ; which are so much the more valuable, as they were instituted loith a 
totally distinct object in view.*'-— 4th Edition, p. 205. 

We could point out other sources of error in the reasoning of 
Baron Liebig, but we will here simply call attention to the fact, 
that in the amount of nitrogen (22 lbs. per acre), which he says 
the fields of Virginia annually yield without manure, we have 
the most satisfactory proof of the inapplicability of any dedaction 
firom such an instance, regarding the requirements of our oton 
cultivated plants. Thus, an average crop of wheat in this country, 
under good cultivation, will contain twice as much nitrogen as is 
here supposed. 

It is in reference to the facts and arguments above alluded to, 
that Baron Liebig concludes as follows, in the sentence which, 
with reference to special points, we have quoted already more 
than once : — 

" Hence it is quite certain, that in our fields, the amount of nitrogen in the 
crops is not at all in proportion to the quantity supplied in the manitre^and that 
the soil cannot be exhausted hy the exportation of products containing nitrogen 
(unless these products contain at the same time a large amount of mineral 






Agricultural Chemistry. 83 

faigredientfl), 6^couM the nitrogen of vegetation i$ furnished bff the atmoephere^ 
tmd not hg the soil. Hence also we cannot augment the fertility of our fields, 
or their powers of production, by supplying them with manures rich in nitro- 
gen, or with ammoniacal salts alone. The crops on afidd dinnnish or increase 
m emct proportion to the diminution or increase ^ the mineral substances 
conveged to it in manureJ^^Ath Edition, p. 210. 

From this short recital, the reader will be able to form a 
jadgment, of what were the prevailing ideas, and what the points 
of question regarding manure, and therefore what was the extent 
of the meaning of Baron Liebig, when he wrote the sentences 
qaoted above, and considered it so essential to attribute a pr^ 
ponderating value and importance to the mmeral constituents 
of manure. And it was in reference to the conclusions arrived 
at by the facts and arguments above referred to, taken in con- 
nection with a consideration of the sources and mineral composi- 
tion of animal excrements, that Baron Liebig in the preface to 
the 3rd and 4th editions of his main work (published respectively 
in 1843 and 1847), said :— 

^ And I am now, for the first time since the completion of these labours, 
in a situation to give a' simple and determinate expression to my Tiew of the 
origin of animal excrements, and of the cause of their beneficial effects on 
the growth of all vegetables." 

To vindicate himself, however, from the imputation now made 

by most writers on the subject, that in these arguments and 

conclusions he has underrated the value and importance of 

nitrogen or ammonia within the soil. Baron Liebig quotes in his 

**iVina2)fe«," recently published, the following sentence, occurring 

in the same chapter of his work as that from which we have 

made the extracts given above. 

** In order to obviate any misunderstanding, we must again draw attention 
to the fact, that this explanation is not in any way contradicted by the efiects 
produced on the application of artificial ammonia, or of its salts. Ammonia 
u, and will continue to be, the source of all the nitrogen of plants ; its supply 
is never bjurious ; on the contrary, it is always useful, and, for certain 
purposes, indispensable.*'— 4fA Edition, p. 212. 

This vindicatory sentence, quoted from his previous work. 

Baron Liebig now adduces with the following preface :— 

" In order not to excite new doubts, and in order to put an end to a mis- 
^derstanding, which 1 thought, but vainlg, as it appears, I had rendered 
mpossible in my work, I repeat here what I said in that toork,** — Principles, 
p. 107. 

It would have been more candid if Baron Liebig had given 
the paragraph in question to the end ; for, in what immediately 
Buceeeds to the sentences which he here brings forward, is 
contained the clearest proof that there has been no misunder- 
standing such as he here complains of.* The continuation in his 
work is as follows : — 

* Mr. Maskelyne also, in the 'Saturday Review* of December 15, gives the 



y 2 



84 Aifncnltural Chemidry, 

" But, at the same time, it is of great importance for agriciiltiire, to know 
i¥ith certainty that the supply of ammonia is minecessary for most of om* 
cultivated plants, and that it mfy he even super/itums, if only the sail ccniaim 
a siifficient supply of the mineral food of plants, when the ammonia required 
for their development tvill be furnished by the atmosphere, Jt is also of 
importance to know, that the rule usually adopted in France and in Germany 
of estimating the value of a manure according to the amount of it* nitrogen, 
is quite fallacious, and that its volume does not stand in proportion to its 
mtroge7i.''^ \ 

Such, then, were the reasonings and conclusions of Baron 
Liebig regarding the relative value of the constituents of manure, 
founded, to a great extent, upon a consideration of the experi- 
ments of M. Boussingault on the chemical statistics of rotation, 
and in opposition to the opinions arrived at by the latter in 
regard to those experiments. On the chemical principles involved 
in rotation itself Barron Liebig thus expresses himself: — 

** In a more confined sense, the time of fallow may he limited to the intervals 
in the cultivation of cereal plants ; for a magazine of soluble silicates and of 
alkalies is an essential condition to the existence of such plants. The cultiva- 
tion of potatoes or of turnips during the interval will not impair the fertility 
of the field for the cereals which are to succeed (supposing the supply of 
alkalies to he sufficient for both), because the former plants do not require 
any of the silica necessary for the latter.''--4f A Edition, p. 133. 

Again, after many pages of illustration of the importance of 
the mineral, or soU-proper constituents, he says : — 

" It follows, then, from the preceding observations, that the advantage of 
the alternate system of husbandry consists in the fact that the cultivated 
plants abstract from the soil unequal quantities of certain nutritious matters. 

" A fertile soil must contain in sufiicient quantity, and in a form adapted 
for assimilation, all the inorganic materials indispensable for the growtn of 
plants. 

'* A field artificially prepared for culture, contains a certain amount of these 
ingredients, and also ot ammoniacal salts and decaying vegetable matter. The 
system of rotation adopted on such a field is, that a potash-plant (turnips or 
potatoes) is succeeded oy a silica-plant, and the latter is followed by a lime- 
plant.''— -4<A Edition, p. 169. 

And in his ** Principles," recently published, he sums np the 
rationale of rotation in his 35th Proposition, thus : — 

"On the unequal quantity and quality (solubilitv, &c.) of the mineral 
constituents, and on the unequal prouortions in which thev are required for 
the development of the difi'erent cultivated crops, depends the rotation of 
crops, and the varieties of rotation employed in different localities.** — P, 29. 

Here, then, we have distinctly enough set forth, even up to 
the present time, Baron Liebig's mineral theory of rotation ; and 
we have already seen, that he has pronounced as " thoroughly 
erroneous," M. Boussingault's conclusions as to the greater 
dependence of the cereals grown in our rotations, upon nitrogen 

sontende mthout the continuation, to illustrate our unfairness in not folly 
Cjuot ing Baron Liebig 1 



Ayriculiural Chemistry. 85 

provided in the soil, and as to the greater reliance of the 
leguminous crops grown in alternation with them, upon atmo- 
spheric sources of nitrogen ; — and also his conclusion that the 
amount of produce in the rotation is in proportion to the 
nitrogen in the manure. 

Now, if M. Boussingault really did intend to say, " that legumi- 
noDs plants alone possess the power of appropriating, as food, 
nitrogen from the air, and that other cultivated plants do not at 
all possess this property," he certainly here committed an error ; 
that is to say, if his meaning were, that the latter would assimi- 
late only the amount of nitrogen conveyed to the soil in the form 
ofmanurey and that they would not give a certain annual average 
produce independently of such supply. Such an error, if it 
were committed, would easily arise from the fact, that in his own 
experiments on the growth of wheat by means of manure, in 
which he only recovered in the produce about as much nitrogen as 
the manure contained, he had not by the side of his manured plot 
one growing the same crop without manure. By such a col- 
lateral experiment, he would have learned how much of his total 
produce was due to soil and season, independently of direct 
manure, and how much to the latter. Had he, indeed, possessed 
these data, he must then have concluded, that the cereals did 
accumulate a limited amount of nitrogen from natural sources ; 
and that the ijicrease beyond this amount, was obtained only at 
a cost of much more nitrogen in the manure than was stored up 
in the increase of crop produced by it. And had M. Boussin- 
gault clearly appreciated this fact, regarding which, since the 
time he wrote, so much evidence has been recorded, he would 
scarcely, whilst so prominently calling attention to the distinctions 
which he observed in regard to the requirements of the cereals 
and leguminous plants in his rotations, nevertheless, have said, 
in reference to those admirable results, that they rather afforded 
a view of the circumstances of an entire rotation, than threw any 
light on the special share in rotation of the individual crops. 
Nor could he have failed to see, that in those distinctions which 
he really did point out, was the very key to the chemical prin- 
ciples involved in rotation of crops. M. Boussingault, indeed, 
distinctly called attention to the fact, that the benefits derived 
from growing a leguminous crop before a cereal, must to a great 
extent arise fi'om the amount of organic matter thus accumulated 
within the soil as a manure for the latter. He further pointed 
out, that the very restorative leguminous crops, nevertheless 
take from the soil a very large proportion of some of the most 
important of the mineral constituents ; and from the latter fact 
he seems to have drawn the inference that in the choice of our 
succession of crops, care should be taken to make the selection 



86 Agi'iculiural Cliemisiry. 

with clear reference to the amount of the various mineral con- 
stituents removed from the land in the different crops. Was there 
not, however, we may ask, in the very fects here recorded, namely, 
that notwithstanding the exhaustion of minerals the clover was 
still so good a preparative for wheat — ^was there not in these 
coincident facts, that which would rather lead us to suppose, that 
the benefits arising from the order of succession merely of re- 
storative and other crops, was little dependent on the mineral 
requirements of the individual crops ? — and in fact, that if only 
the restorative crop, with its large demand for minerals, were 
enabled to grow luxuriantly, we might then conclude, that the 
soil was so rich in available mineral constituents, that the suc- 
ceeding crop with its comparatively meagre demand, and to 
which the former is known to be so subservient by the matters 
it leaves behind it, was little likely to find them wanting ? 

Baron Liebig, however, carries the mineral explanation of ro- 
tation .very much further, when he says, in regard to M. Boussin- 
gault's opinions : — 

" But all these conclusions are thoroughly erroneous; for, if they were mi 
eo, it must follow that potass, lime, and silica plants, unless they belonged to 
the leguminosa, would not produce any nitrogen, unless they were supplied 
with manure containing that element." — ith Edition, p. 208. 

Nor could Baron Liebig have reasoned as he did in r^ard to 
the analysis of M. Boussingault's rotations, had he, not only 
dwelt more upon the composition of each individual crop and 
their relations to each other, but at the same time recognised 
that which he will not even now admit, namely, that any in- 
a'eased produce of wheat is obtained only at the cost of more 
nitrogen provided in the manure than is recovered in that 
increased produce. 

But let us see how the rrdnerai theory of rotation, as expressed 
in Baron Liebig's 35th Proposition, is consistent with the evi- 
dence of direct experiment. 

In Table VIII. we have the chemical statistics of three actual 
rotations; in each of which the course consisted of Swedish 
turnips, barley, clover, and wheat ; and in all cases the entire 
produce of the swedes (both leaf and root) was removed from 
the land. 

In rotation 1, the course commenced without any manure at all. 

In rotation 2, it commenced with a manure of superphosphate ' 
of lime alone. 

And in rotation 3, with a liberal mixed manure, containing 
rape-cake, ammonia-salts, potash, soda, and magnesia, and 
superphosphate of lime. 

The constituents per acre which are calculated are — dry organic 
matter, nitrogen, total mineral matter, and the phosphoric acid, 



Aiiriculhiral Oiemisb'y. 



87 



potash, lime, magnesia, and silica contained in the latter. The 
dry organic matter, nitrogen, and mineral matter, are in most 
cases calcolated from direct determinations, made on the produce 
of the different plots; but in any cases where such direct results 
were not attainable, the averages of allied cases have been taken. 
The constituents of ash are, however, in all cases calculated from 
an adopted average percentage, deduced from a consideration of 
all recorded analyses with which we are acquainted,* taken in 
connexion with the analyses of similar ashes made in the labora- 
tory at Rothamsted : — 

Table VIII. — Chemical Statistics of three Rotations, constituents per acre 
(Ihe.). Entire produi*e of Swedes (leaves and roots) carted off the land. 




Rotation 1. — Swedes, nnmanured. 






Ihy organic 

Nitrogen 

Mineral 

Phosphoric acid 

Potash 

Lime 

Magneda 

SiHca* 



• • • • » • 


2460- 


3872- 


4325- 


4316- 


• •  • V • 


64- 


62- 


142- 


57- 


B • • • «  


127- 


179- 


417- 


217- 


•  a »• • 


11-6 


211 


31-3 


24-6 


«• • •  a 


33-8 


31-3 


83-5 


38-4 


• • • •  * 


19-3 


12-6 


126-2 


11-4 


•• • ' •• 


3-3 


72 


36-5 


7-2 


• •  • • • 


20 


921 


12-5 


126-8 



notation 2. — Swedes, by Superphosphate of Lime. 



Dry organic 

Nitrogen 

Mineral ... ••« 


8945- 

98- 

228- 


2810- 

38- 

129* 


4450- 
146* 
429- 


4583* 

60- 

238- 


Phosphoric acid 

A UlMinll aa. •.. a*a ••• ••• 

^llUQ •.. aa. ... aa. aaa •*• 

"■'•JjieHia aaa a*. a«« ••• ••• 

Silica* 


20-7 

610 

34*4 

5-9 

3-7 


160 

22-8 

8-8 

5-3 

65-3 


32-2 

86-9 

128-8 

36-6 

12-9 


26-7 

36-5 

12-4 

7-9 

137-9 



Botation 3.— 


-Swedes, by mixed Manures. 




Inorganic 

Nitrogen 

'UIMSIaI ,,, t,t ..a .a aaa 

Phosphoric acid 

Potash 

lUC aaa aa. aaa ••• ••• «•• 

'■sgnesia « • 

BIllCB aa. *•• ..• ••. ••• 


4984- ' 3269- 
139- 45 
227- 1 146- 

19-9 , 17-8 

58-3 . 26-6 

36-9 ' 100 

6-0 60 

3-7 ; 73 8 

i 


5164- 
170- 
498- 

37-4 
99-7 
149-5 
42-3 
149 


4620- 

69- 

234- 

256 

35*6 

12-2 

7-6 

136-6 



• In some cases taTid is obviously included with the ** .silica." 



88 Aijncultural Chemist)^, 

Now it is obvious, that if the benefits of rotation depended on 
the " unequal quantity and quality (solubility, &c.) of the mineral 
constituents, and on the unequal proportions in which they are 
required for the development of the different cultivated crops," 
and if the benefit of the clover here introduced between the 
cereal barley and the cereal wheat, were the less exhaustion of the 
minerals by the leguminous crop, we should surely find, that in 
the cases here given, the latter had taken out of the land less of 
the important mineral constituents than either the barley grown 
before it or the wheat which succeeded it. But what are the facts 
of the case ? In every case there is more — and in most cases very 
much m/yre — of phosphoric acid, potash, lim^^ and m/ignesia^ taJcen 
off tlie land in the clover crop, than in either the barley or the wheai. 
And it should be remarked, that the produce of wheat obtained 
after the interposition and heavy mineral exhaustion of the clover, 
was in every case a very full one ; in fact, it was such in amount 
that we have every reason for concluding, that it was nearly double 
what would have been obtained had it been grown immediately 
succeeding the barley. The fact is, therefore, that we have r 
very much larger produce of wheat after this great drain from tl j 
land of phosphoric acid, potash, lime, and magnesia, than we 
should have had without the intervention of the crop which ex- 
tracted them. But there is one mineral constituent, namely, 
silica, which was taken out in very small quantity by the clover, 
though in very large quantity both by the preceding barley and 
the succeeding wheat. 

If, therefore, the benefit of the intervention of the clover, de- 
pended upon its exhausting less of certain mineral constituents 
of the soil than the wheat which was to succeed it, it could only 
be in reference to silica that it had this beneficial action. But Baron 
Liebig has told us, that, provided there be a sufficiency of avail- 
able alkali in the soil, there will never be a deficiency of available 
silica. And if this be so, since we find that in every case, the clover 
found in the land nearly three times as much potash as was required 
by the succeeding heavy crop of wheat, we can hardly attribute 
the benefit of the clover upon the wheat crop to its conservation 
of soluble silica in the soil for the latter. But further, since we 
know, that immediately aiter the barley, we could have ob- 
tained a crop of wheat nearly, if not quite, equal to that which 
was obtained after the intervention of the clover, by means of 
ammonia salts, or nitrate of soda alone, it is clear that, unleas 
the action of the latter manures was to render silica soluble and 
available for the crop, the beneficial action of the clover can 
have nothing whatever to do with the increase in the soil for 
the wheat crop of any of the important mineral constituenta 
enumerated. 



Agrkidiural Chemlatrif, 8'J 

Taking together, then, the now established facts, that the 

supply of aviolable nitrogen to a cultivated soil, greatly increases 

the produce of wheat, — ^that the clover, which has the same effect, 

has rendered the soil much poorer in all the important mineral 

constituents required by the wheat, except silica, — and that the 

clover again is known to yield twice or three times as much 

nitrogen per acre as a cereal grain when equally provided with it 

by manure, and that it also leaves a large amount of organic 

residue in the land, — ^have we not in these facts, sufficient ground 

for concluding, that the beneficial effect of the leguminous clover 

has been the accumulation from atmospheric sources within the 

soil Oself^ of availdble nitrogen for the increased growth of the cereal 

grain ? And have we not in this tact, taken in connection with 

that of the much larger amount of nitrogen required in manure 

than is obtained in an increased produce of wheat obtained by 

its use, the clearest key to the benefits of the w>-calledfaMow crops 

in alternation with grain ? Have we not in these facts the 

clearest proofs, that the rotation of crops does not depend '^ on the 

Bnequal quantity and quality (solubility. Sue.) of the mineral 

constituents, and on the unequal proportions in which they are 

required for the development of the different cultivated crops ? '^ 

And how, we would ask, if an adequate increased growth of com 

he only attainable by the accumulation of available nitrogen vnthin 

ike soU — and if one of the chief means of the farmer to this end 

were a rotaiion of cropSy by which he is enabled ^^ to produce 

manure for his com crops, that is, for the growth of his saleable 

produce " — and if the great object to be attained in our time is 

*' to substitute for a rotation of crops a rotation of the proper 

manures " — how, we would ask, would an adequate increase of 

grain be possible under such circumstances, by the supply of a 

rotation of manures from wUhoviy founded on a knowledge of the 

composition of the ashes of the crop to be grown ? 

To resume — as the result of our whole inquiry we conclude : — 

1. That the manure indicated by the resultant requirements of 
British agriculture has no direct connexion with the composition 
of the mineral substances collectively found in the ashes of the 
produce grown on, or exported firom the farm ; and that the 
direct mineral manures which are required, are not advan- 
tageously applied for the direct reproduction of the exported com, 
but should be used for the green or fallow crops — one of whose 
offices it is, to collect from the atmosphere, or to conserve on the 
farm, available nitrogen, for the increased growth of the cereal 
grains. 

2. That the nitrogen required to be provided within the soU for 

this purpose, is far greater than that contained in the increase of 

produce obtained by it. 

o 



90 AtjricuUiiml Chemist nj. 

3. That the chemical effects otfaUow, in increasing the growth 
of the cereal grains^ are not measarable by the amount of the 
additional mineral food of plants liberated thereby, these beings 
under ordinary cnltivation^ in excess of the assimilable nitrogen 
existing in or condensed within the soil in the same period of 
time. The amount c^ the latter therefore — ('j.o.) the avaihMe 
nitrogen — ^is the measure of the increased produce of grain 
which will be obtained. 

4. That the beneficial effects of roiaHon, in increasing the pro- 
duction of saleable produce (so far as they are chemical), are not 
explained by the fact of one plant taking from the soil more of 
the different mineral constituents than another, but depend on 
the property of the so-called green orfalUno oropB of bringing, 
or conserving, upon the farm, more substance rich in nitrogen 
than is yielded to them in manure ; whilst the crops to which 
they are subservient, are both largely exported from the fiirm, 
and yield in their increase considerably less nitrogen than is 
given to them in manure. 

5. In a word — ^that, in the existing condition of British agri- 
eulture, a full production of the saleable cereal grains^ with other 
exportable produce, is only attainable, whether by manwres^faUow^ 
or TotaMony provided there be an accumulation of available nitro* 
gen within the soil itself. 



Hothamstedy Herts, December, 1855» 



nuVTU) BT 

■PormirooDB and co., vvw-trmrr sqcabb 

LOKDOK 




ON 



THE GROWTH OF WHEAT 



BT THB 



LOIS WEEDON SYSTEM, ON THE 
EOTHAMSTED SOIL; 



AND ON 



THE COMBINED NITROGEN IN SOILS. 



By J. B. LAWES, F.R.S., F.C.S., 



AND 



Dr. J. H. GILBERT, F.C.S. 



LONDON: 

PRINTED BY W. CLOWES AND SONS, STAMFORD STREET, 

AND CHABING GROSS. 

 1857. 



REPRINTED BY SPOTTISWOODE A CO., NEW-STREET SQUARE, 

1894. 



I 



**.- 



FROM THB 
JOURNAL OF THE BOYAL AOBICULTUBAL SOCIBTY OF BKOLAND, 

VOL. XVIL, PART IL 



^ 



n 



ON THE . , , 

LOIS WEEDON PLAN OF GROWING WHEAT j 

AND 

ON THE COMBINED NITROGEN IN SOILS. 



In the year 1849, when wheat was selling at hs. per bushel, and 

the " Sttmt British Farmer " was complaining of the badness of 

the times, and felt somewhat perplexed how to pay his rent and 

retain a little surplus, there appeared a pamphlet entitled A 

Word in Season, in which the author explained his method of 

growing wheat year after year without manure ; and he promised 

to those who would adopt his system and follow his directions, a 

profit of 4Z., bl., or 61. per acre. Of the numerous essays which 

have been published on agricultural subjects of late years, few • 

have attracted more attention than this. Commencing its career 

in 1849 as a pamphlet of less than twenty pages, it has since 

gone through edition after edition, until now, in 1856, we find the 

Bubject much extended, and presented as a book of 120 pages. 

In this little book, entitled Lois Weedon Hiishand/i-^/, the 
snthor, the Rev. S. Smith, goes into considerable detail not before 
given, as to his mode of growing root and other green crops. 
Bat confining attention for the present to wheat, it may ba ob- 
served, that although Mr. Smith has from time to time made 
various important alterations in the detail of the operations by 
which his system is to be carried out, he has in no way deviated 
from his original principle of growing this crop year after year in 
the same field ; the land being subdivided into alternate strips of 
crop and fallow, the portion cropped one year being fallowed the 
next, and so on. A great number of intelligent agriculturists 
have visited the Lois Weedon farm, and, after an inspection of the 
crops growing on the plans there adopted, have generally been 
satisfied that the produce has been what the published accounts 
had stated it to be. Yet it is somewhat singular that those who 
have endeavoured to follow the directions given, on other soils, 
have generally been unsuccessful. 

The object of the present paper is to give an account of some 
experiments which have been in progress for several seasons past, 
with a view of testing the applicability to the Hothamsted soil of 
^he system described in A Word in Season. And besides dis*- 
cusaing the experiments themselves, we propose to consider some 
points of interest which the principle of the Lois Weedon system 
involves ; for although doubts may be entertained by practical 
^en as to the possibility of cultivating large farms on such a plan, 
it must still be admitted that the results which have been obtained 
l>y the Rev. Mr. Smith himself are calculated to impress upon us 

A 2 



<iA 



4 The Lots Weedan PUm of Ckomng WheaL 

most important lessons regarding tke rationale of admitted agri- 
cultural facts and practices. They teach us, too, how great, in , 
certain kinds of soil, must be at once the inherent wealth and the 
power of accumulation and of yielding up to the growing crop 
the constituents upon which it feeds. 

In the year 1851 about three acres were selected for our pur- 
pose, in a field adjoining that which has been devoted for so 
many years to the continuous growth of wheat with and without 
artificial or other manures. The soil of these fields is a heavy 
loam, with a subsoil of stiff reddish yellow clay, which rests upon 
chalk. The depth from the surface to the chaJk is perhaps never 
less than six or seven feet, and frequently twice as much ; the 
natural drainage is, however, good. These soils, without being 
of high, are still of good average quality, and capable of growing 
good wheat crops. They are well suited, therefore, to test the 
degree of applicability to other soils of plans proposed for ex- 
tensive adoption in the cultivation of that crop. The field selected 
was under wheat in 1850, and was a bare fallow in 1851, prior to 
commencing the Lois Weedon operations in the autumn of that 
year. For the first crop the land was ploughed and harrowed in 
the ordinary way, and then set out in three feet strips ; of these, 
every other one was sown with three rows of wheat a foot apart, 
and the intermediate ones were left as falioiv spaces^ to be prepared 
for the second year's crop during the growth of the first. It will 
be seen, that, as each strip was three feet wide, and as the three 
rows at a foot apart would only occupy two feet, there were in 
fact/owr-feet fallow spaces, as is recommended by Mr. Smith in 
some cases, instead of only three, as adopted in his own practice. 
The first sowing was in September 1851, and, not having the 
special implements since recommended for carrying out the plan 
on the large scale, the seed was dibbled iny at a distance of two to 
three inches iEtpart in the rows. One portion of the experimental 
ground had a single seed dropped into each hole, thus conforming, 
as far as possible, to Mr. Smith's mode of sowing single seeds at 
two to three inches apart in lines made with his presser ; another 
and larger portion of the plot had two seeds in each hole. It was 
found that the one^seed portion took little more than half a peck 
of seed per acre, that is, haU a p^k to the moiety of the acre 
seeded at one time. The Rev. Mr. Smith, however, seems always 
to have calculated upon two pecks of seed being used, even though 
sown, as above described, in single grains, at two to three inches 
apart in the rows. And although, where we sowed two seeds in 
each hole, or twice as much as is recommended, we got on little 
more than a peck to the acre, yet it is but justice to Mr. Smith 
to state, that he now finds a more liberal seeding necessary for 
safety and security from blight, to which, as will afterwards be 
seen, our produce obtained on this plan was so subject. 



Tlie Lois Weedon Flan of Qrowing Wheal, 6 

It may here be further mentioned, that not having the special 
implements — the *' presser implement" the driM " to drop seed by 
seed into the hard channels" the " roller implement" the " horse-hoe 
implement^* and the " scarifier and harrow implement " — which 
are recommended in Mr. Smith's later editions for carrying 
oat his plan on an extensive scale, we were obliged to adopt 
his earlier methods, by which, however, his records show, that 
he obtj^ined as good, if not as economical results, as by his 
later ones. 

Before the adaptation of special implemerrts, Mr. Smith's plan 
comprised "one double digging," '*two single diggings, with 
fork," " pressing, sowing, hoeing," &c. 

The following is a concise statement of the operations carried 

out at Rothamsted, for each of the four crops respectively, which 

have been obtained in the course of this experiment. And it may 

here be premised, that one of the three acres was, for the sake of 

comparison, set apart for alternate wheat and summer fallow — 

the fallow being cultivated according to the common custom of 

tke neighbourhood. 

Far First Crop, 1851-2 :— 

Wheat, harvest 1850; summer fallow 1851; ploughed, har- 
rowed, &c., in the ordinary way, and sown with one seed, and two 
ieeds^ as above described, September 1851 ; hand-hoed twice, and 
weeded as other crops. Crop foul, poor, and much blighted ; 
cut in August 1852. 

Common fallow acre all sown autumn 1851 ; seed drilled at 
the rate of about two bushels per acre, in rows 9 inches apart ; 
hoed and weeded as usual. Crop heavy, but somewhat blighted. 

For Second Crop, 1852-3 :— 

The fallow intervals, which were not sown, trenched 14 to 15 
inches in December 1851 ; forked in spring, and again before 
Bowing ; occasionally spudded, but became foul and crusted over 
during the summer. Seed sown as for first crop, October 1852 ; 
hoed twice, and weeded as usual. Crop not clean, poor, and 
blighted ; cut September 1853. 

Common fallow acre, all fallow in 1852-3. 

For Third Crop, 1853-4 :— 

Stubble of harvest 1852, trenched 14 to 15 inches December 
1852 ; forked in the spring ; spudded occasionally, and again 
forked before sowing. Sown as above, October 1853; hoed 
twice, and weeded as usual. Crop pretty clean, but poor, and 
Uighted; cut September 1854. 

Common fallow acre all drilled, as before ; hoed and weeded as 
usual. Crop very heavy, somewhat blighted. 

For Fourth Crop, 1854-5 :— 
Stubble of harvest 1853, trenched 14 to 15 inches in winter 



• «  • « 

€ 'The Lois Weedon Plan of Of owing Wlieai', 

1853 ; forked in the spring ; occasionally spudded, and scarified 
before sowing. Seed sown as usaal, September 1854; twice 
boed, and weeded as usual ; moulded up with the ploog>b in June. 
Crop clean, but poor, and blighted ; cut September 1 865. 

Half only, of common fallow acre, drilled as usual for season 
1854-5 ; hoed and weeded as usuaL Crop small, but much less 
blighted than before. 

In the following Table (I.) are given the results — 

Of the four years' trial of the Lois Weedon plan ; one portion 
with " one seed,^^ and another with " two seeds" in each hole. 

Of the " common fallow " acre, drilled with about two bnshels 
of seed per acre. 

And, for the sake of comparison, the produce in each of the four 
years, of the continuously unmanured and continuously cropped 
portion, in the adjoining experimental field. 

This Table (I.) shows, that in each of the four years a larger 
crop was obtained where two seeds were sown in each hole than 
where one only was sown j and a reference to the weight per 
bushel, proportion of ofial grain, and proportion of grain to straw, 
will show that the ^* two^eed " crop was also invariably somewhat 
better as to quality. As before observed, however, it is only due 
to the Rev. Mr. Smith to say, that ^^for the sake of the sample and 
for safety saJce," he now recommends the seed to be sown thicker 
than he did formerly ; though even in the later editions of the 
Word in Season, he still advised that the seed should be dropped 
singly, at two to three inches apart in the rows. But, even with 
•the two seeds y the crop is in every case quite insignificant ; and it 
should be noticed that it is only in the first year — that is, before 
the subsoil was brought up — that this thin dibbled crop was 
larger than the comparatively thickly drilled one on the con- 
tinuously cropped and continuously unmanured plot in the ad- 
joining field. Further, comparing the best of the two, namely, 
the two-seed crop, with the drilled one after common fallow, we 
find that the latter in each year gives from twice to thrice the 
amount of produce of the former. 

With regard to the drilled crop on the common fallow, it should 
be remarked that, in the first season (1851-2), the whole acre was 
sown ; in the second season the whole acre was fallow ; and in 
the third the whole was again sown. But, as this plan only gave 
a crop for comparison every other year, the plot was divided info 
two portions after the harvest of 1854, which were to be cropped 
or fallowed alternately. Comparing together the produce of this 
common fallorv j^orthn, with that of the contmuoiisly unmanured 
plot in the adjoining field, we see that, in 1852, the common 
fallow gives nearly three times as much produce; in 1854 it 



The Zoit Weedon Plan of Oromng Wheat. 



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8 The Laia Weedon Plan of Ch'owing Wheat, 

gives rather more than twice as mach ; and, as we shall see in 
the next Table, in 1856, it gave once and a half as much aa the 
continuously cropped and continuously unmanured plot. 

In contrast to these very marked effects of foLloWj it ia inte- 
resting to observe, that when in 1855 this common fallow plot 
grew wheat after wlveai,^ the produce was, within half a bushel of 
grrain and within half a hundredweight of straw, the same aa was 
obtained on the continuously unmanured plot of the adjoining 
field in that same season, which was the twelfth in suocession of 
wheat on that plot. So perfect an illustration could hardly have 
been expected, of the fact of the eqaal wheatngrowing candtlian to 
which these two adjoining fields were reduced by the grow^th of 
the crop ; or, what is the same thing, of the absolutely equal 
condition for practical purposes, to which these two soils were 
brought, in relation to the climatic resources of growth of one 
and the same season. 

Lastly, in regard to these effects of faMow^ it may be noticed 
that in no case is the amount of produce found to be equal 
simply to the sum of the continuous unmanured produce of the 
season of the fallow and of that of the succeeding crop. That is 
to say, the produce after foUlow is not simply the produce of that 
particular season, taken together with that of the immediately 
preceding season. It is the result, not only of the unexpended 
resource of the fallow year, and of the resources (atmospheric 
and terrestrial) of the actual season of growth, but there is 
also an effect of the season of growth (whether for increase or 
decrease) reacting itself upon a two yeara^ resource ; and conse- 
quently throughout the season, upon a different stage of progress 
and area of food collectors of the growing plant. Or, the differ- 
ence between the actual produce after fallow and the simple sum 
of the produce of the two years may further depend upon the 
more or less favourable adaptation of season as regards the 
healthy development of the crop, as distinguished from the mere 
amount of the available resources of the soil and seasons. 

But with this very marked increase of crop as the result of 
the common fallow, how is it that the more expensive processes 
of trenching and forking, with the thinner seeding, &c., which 
on the soil at Lois Weedon yielded such excellent results, have 
on the Rothamsted soil been so ineffective ? 

Undoubtedly the too thin seeding has been one cause of this. 
It is also certain that the same amount of labour expended upon 
the Rothamsted soil as upon the Lois Weedon one, was quite 
inefiicient to get the same amount of staple and of exposure of 
surface to atmospheric influences. It may be here stated, how- 
ever, that the trenching at Rothamsted cost on the average about 
once and a half as much as is estimated by Mr. Smith. It is 



The Lois Weedon Plan of Growing Wheat 9 

granted too, tiiat the more recent recommendation, namely, that 
of moalding up the growing crop in June, was only adopted in 
the last year of the experiment (1855), and then with little effect. 
Bat as the earlier recorded success at Lois Weedon was obtained 
without this — however great the improvement, as undoubtedly 
it is — it certainly was not an essentisd in the original plan. 

With these unfavourable circumstances admitted then, we 
again ask, -what is the rationale of the failure, which these cir- 
cumstances have had their share in causing? Was the available 
mineral food for the crop deficient in this tumed-up raw clay 
subsoil, with the good upper staple, weathered perhaps for cen- 
turies, noi?v turned below for the descending roots to play in ? 
Or, was it rather that the upper staple being now buried, or 
much intermixed with the subsoil, there was rendered available 
from its own, and from fresh atmospheric resources, less of the 
normally atmospheric food of the crop ; and th^t the raw sub- 
Boifl, but recently exposed to direct atmospheric influences, 
was able, so to speak, to prepare for the plant, and to accumulate 
ht it in an available form, also less of the normally atmospheric 
ibod of plants ? 

On conamunicating our failure after four years* trial to the 
Rev. Mr. Smith, he suggested the probability that it was due to 
a want of a sufficient amount of the mineral constituents of the 
wheat-plant being rendered soluble and available ; and that, in 
this case, the requisite supply of mineral matter should be made 
up by manure ; believing that then, the soil having become 
pulverised and porous, there would be an abundant supply of 
organic substance provided by the atmosphere. 

That the soil in question was not relatively deficient in soluble 
and available mineral food, and that, under certain circum- 
stances, there was provided an abundant supply of organic food 
for a very much larger crop, was proved much more conclusively by 
the produce of the common fallow acre than any analysis of the 
soil could prove it. To test, however, in another way, what was 
the nature of the deficiency of the two-acre plot, trenched to a 
depth of 14 to 15 inches and afterwards forked, it was, after the 
harvest of 1855, divided into four portions, in such a manner that 
each of the four had an equal proportion of the trenched and forked 
&Uow and of the stubble ground. The whole was then ploughed 
and prepared for sowing in the ordinary way : one portion was 
left unmanured,* the second received minersd manure only, the 
third ammonia-salts only, and the fourth both mineral con- 
Btitaents and ammonia-salts. All four of the plots, together 
with half of the common fallow acre by their side, were then 
drilled with about two bushels of seed per acre in ike ordinary 
^ay. 



10 The Lois Weedon Plan of Qromng Whecd. 

In the following table are given the results of this experiment, 
obtained in the season 1855-6 just passed. For the sake of com- 
parison, there is first given, in the upper portion of the table, the 
average annual result for the four previous years, of the ^^one 9eed^ 
of the ** two seedy" and of the " drilled common fallow " plots ; and 
also the average for the same years of the continuously un manured 
plot in the adjoining field. And, in the lower portion of the table, 
is given the produce at the last harvest (1856), in the adjoining 
field (where wheat is grown year after year without or with simUar 
manures successively), of the continuously unmanured plot, and of 
the plots having the same manures as those now applied, to the 
Lois Weedon plots. The manuring of the plots was, per acre, 

as under : — 

1. Unmamired. 

2. Mineral Manures only, 

* dOO lU. sulphate of potash. 
200 ,y y, soda. 

100 ,, „ magneaia. 

200 „ calcined bone. "X 

160 ff sulphuric acid (brown), j 

8. AmmonichsalU only. 

200 lbs. sulphate of ammonia. 
200 „ muriate of ammonia. 

4. Minerals and Ammovwi-salts* 

800 lbs. sulphate of potash. • 

200 „ „ soda. 

100 „ ,f magnesia. 

200 „ calcined bone. 1 

160 y, sulphuric acid (brown). / 

200 „ sulphate of ammonia. 

200 „ muriate of ammonia. 

Looking at the middle division of the table, which shows the 
efiects of manures, &c., on the trenched and forked land, and also 
the produce on the common fallow portion, it must be borne in 
mind that, in point of fact, rather more than half of the former 
was fallow, and less than half of it under crop, in the previous year; 
and that, moreover, smaller amounts of produce had been taken 
from this than from the common fallow portion during the four 
previous years. In comparing, therefore, the produce now ob- 
tained by thicker sowing, manure, &c., on this land with that on 
the common fallow plot, we must remember that the former was 
also in great part fallowed, and that the whole of it was less 
exhausted by previous cropping than the common fallow portion. 
Keeping this in mind, it is seen that the unmanured, trenched, 
and part-fallow portion, gave within a bushel as much grain, and 
actually a few pounds more straw and more total produce than the 
common fallow. It is evident^ therefore, that the less produce on 



'The Lois Wesdon Plan of Or&uring Wheat. 








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12 . The Lois Weedmi Plan of Growing WheaJt. 

the trenched portion in the previous years, was in greater measnre 
due to the thin seeding on the comparatively poor and raw tnmed- 
up subsoil, than to any relative deficiency or want of available 
condition of the food of the plant within the soil — provided only 
that a sufficiently healthy early development, and a sufficiently 
wide distribution of the underground feeders of the crop, were 
but obtained. 

Taking the produce of this unmanured portion thus explained, 
as the standard by which to compare the effects of manores on 
land in the same condition, we find that — 

" Mineral manures only " — gave an increase of not quite 2 J 
bushels of total grain, and of only 284 lbs. of straw. 

^^ Armnonia-saUs only^* — gave an increase of about 15 bushels 
of total grain, and of 1695 lbs. of straw. 

*^ Minerals and ammonia^saUs^^ — gave an increase of rather 
more than 20 bushels of grain, and of 2757 lbs. of straw. 

These striking results can leave no doubt that the mineral 
supplies in the soil in question were far in excess over the avail- 
able and assimilable nitrogen. A comparison, too, of the middle 
and the lowest divisions of the Table will show that, if we take into 
consideration the very difierent condition of the land in the two 
cases, the effects of these manures on the Lois Weedon or trenched 
plots were perfectly consistent in kind (though of course not equal 
in degree) with those of the same manures in the adjoining^ field, 
where they have been applied, and the crop has been grown for 
many years in succession. 

Hundreds of other experiments, and the whole range of 
recorded agricultural experience, conspire to show, that in 
ordinarily cropped and cultivated soils, the available mineral 
supplies are generally in excess relatively to the available supply 
of nitrogen of the soil and season, in the case of the wheat crop : 
in fact that, excepting in cases of very special and unusual 
exhaustion of the mineral or soil-proper constituents, the direct 
supply of them by manure for wheat does not increase the crop 
in any practicable and agricultural degree, unless there be a 
liberal provision of available and assimildble nitrogen vnthin {ke 
soil. The results given above are a remarkable illustration o{ 
this. Thus, when the mineral constituents alone were added to 
this part fallow and only part crop-exhausted land, they gave an 
increase of only 438 lbs. of total produce ; but when the same 
mineral constituents are added to the same soil with ammonior 
salts, the increase over and above that by ammonia-salts alone 
is 1368 lbs., instead of only 438 lbs. Here, too, is a sufficient 
incidental proof that the minerals were added in an avaiUxhle 
/orm;— indeed, that they only required sufficient available 
nitrogen within the soil to yield a larger crop than would be 



r 



The Lois Weedon Flan of Growing Wheat. 13 

obtained in the average of seasons on sach soil by the ordinary 
means of farming. 

But taming now from the effect of the mineral constituents to 
that of assiTnilable nitrogen in manures, we have in these simple 
experiments the best answer — namely, that of direct contrary 
hct — ^to those who would endeavour to persuade the farmer, that 
because the soil itself ooutains hundreds of times more nitrogen 
than the largest crop of wheat, therefore the comparatively small 
quantity which is added in an ordinary dressing of manure can 
have little or no effect. We shall recur to the subject of the 
nitrogen in soils further on, should our allotted time permit it. In 
the mean time let it be prominently noted, that whilst the minerals 
alone gave a total increase of only 438 lbs., the ammonia-salts 
alone gave 2573 lbs. of increase ! And again, whilst the addition 
of minerals to ammonia gave an increase of 1368 lbs., the addi- 
tion of ammonia-salts to minerals, on the other hand, gave an 
increase of 3503 lbs. ! 

There can now be little difficulty in deciding, that it was no 
deficiency of available mineral food merely which prevented the 
plant for itself, or the soil in the first instance for it, firom 
acquiring a sufficiency of available and assimilable organic con- 
stituents for the growth of a very much larger crop than was in 
fact obtained from this expensively cultivated land. It was, on 
the other hand, notwithstanding the *^ inexhaustible " supplies of 
the atmosphere, and notwithstanding the enormous amount of 
nitrogen in the soil in some form — it was, notwithstanding these 
— ^a deficiency of available and assimilable nitrogen zvithin the soil 
which restricted the full action of the obviously available minerals, 
and which hence restricted the produce also, to an amount below 
the average of farming. Whilst, only make up this deficiency of 
available nitrogen, and the produce is increased to once and a 
half or twice as much. 

It appears, then, that the same means which afforded the Rev. 

Mr. Smith his early success on the soil at Lois Weedon, were 

quite incompetent to yield a similar result on the soil at Rotham- 

8ted. Nay, these same means, notwithstanding that in our case 

they were much more costly than either Mr. Smith had found them, 

or than the common fallow which we tried by their side, did not 

even attain, for the Rothamsted soil, those mechanical conditions 

without which the necessary actions between soil and atmosphere 

could not be expected to take place. We think it indeed very 

doubtful whether, even if all the more recent improvements in 

the plan could have been fully carried out at Rothamsted, a 

result would have been obtained there at all equal to that at Lois 

Weedon. Certain it is, that soils and subsoils, which may equally 

be included as " clayey " or " h^avy " or " hamy^*' vary almost 



14 The Lois Weedon Plan of Growing Wlieai i 

infinitely in degree, in physical character and texture, and in 
chemical qualities, under the influence of similar managenient 
and of equal climatic circumstances. We think, therefore, that 
considerable caution should be exercised in the application to 
various descriptions of land, of plans which peculiarly rely for 
their success on qualities of soil which are admittedly so variable 
in the degree of their activity. 



Leaving the question of the field-experiments, let us now turn 
to a brief consideration of some points of great practical interest 
and importance, which a careful study of the relations of soil 
and atmosphere to produce, and of the success at Lois Weedon, 
cannot fail to suggest. 

The main peculiarity of the Lois Weedon system of giiowing 
wheat is, that it develops to the utmost (chiefly by mechanical 
means), and relies exclusively upon, the resources of the soil and 
atmosphere without the aid of manure : that is to say, it is 
sought, by the means employed, so to increase the depth of 
staple, and the area of distribution of the underground feeders 
of the crop, and so to increase the surface annually exposed to 
climatic influences, as to cause, not only a greater annual libera- 
tion of mineral constituents from the otherwise locked-up stores 
of them in the soil itself, but also a greater accumulation and 
elaboration, throughout its more porous and root-searching area, 
of the normally atmospheric food of plants, and particularly of 
nitrogen, in an available and assimilable form. 

The principle of relying upon the stores of the soil alone, 
without return, for the mineral food of successive crops, is directly 
opposed to that laid down for the guidance of the agriculturist 
in No. xxxvii. of the Journal of the Royal Agricultural Sodetyj 
by Baron Liebig. He says : — 

" Their heavy crops will perhaps not be rendered heavier by the restoration 
of all the mineral conHtituents, but they will at all events be rendered p^iy 
manent. We shall never have a rational agriculture until, by such experi- 
ments, the law of the fertility of the soil, in reference to time, has oeen 
brought home to the minds of agriculturists." — Journal, p. 313. 

The conclusion of the Rev. Mr. Smith, looking from the 
practical as well as the scientific side of the question, goes rather 
in a different direction. He says to his readers : — 

" The assertion is, that, on wheat land, — that is, on the great majority of 
clays and heavy loams, — no manure is required for wheat on this plan, since 
its food in abundance is there already." — Zot9 Weedon Husbandry, pp. 102-^. 

And again {ibid. 103-4), referring to chemists, he says to his 
readers : — 



avdy The combined Nitrogen in Soils. 15 

*' Ask them plainly, whether the soil and eubsoil of clays and loams, 
general!}' though not uniTersallyy do or do not contain all that is wanted as 
mineral food for the wheat? Ask them, further, whether tillage, and pul- 
Terisation, and gradual exposure, and annual fallows, will not render soluble 
a sufficiency of these substances for your annual need ? If they reply, * Yes,' 
bat demur to the plan, and add, that in time it will exhaust the capital of 
the land, — ask them once more, ' In how long a time? ' And if they answer, 
' ^'hy, in some cases, in a thousand years or more, in others five hundred, 
and in some a hundred/ your rejoinder must be a smile ; for you would 
surely feel, that even a hundred years' supply should satisfy living man." 

Baron Liiebig, in the article above referred to, also indig- 
nantly repudiates the notion that the cause of the efficacy of 
fallow is to be looked for in the increase of the amount of 
ammonia in the soil, or that any specially predominant influence 
was to be ascribed to the ammonia which the soil acquires in 
fallow. The Rev. Mr. Smith, on the other hand, speaking of 
the '' organic " food — " carbonic and nitric acid and ammonia " 
— asks, '* Do not the pulverised intervals of the wheat, in the 
annual fallow, absorb and retain it for use ? " 

It is rather curious, that, with such vital inconsistencies of 
principle and opinion, the wheat-growing operations and success 
at Lois Weedon, and Mr. Smith's interpretation of them, should 
frequently have been brought forward in confirmation of the 
peculiar views of Baron Liebig. The means by which Mn 
Smith obtfdns his large crops of roots also, have recently been 
adduced * as refutation of the views on such points emanating 
from Rothamsted. But the writer in question appears, as the 
rule, to misstate the extent and bearing of every conclusion, and 
even fects, which may happen to come from Rothamsted. For 
OUT own part, careful observation and inquiry on more than one 
visit to the spot, as well as the perusal of Mr. Smith's publica- 
tions, lead us to say, that we know of no experience more cal- 
culated to confirm the opinions we have held in this Journal 
regarding the requirements of growth of full crops of wheat on the 
one hand, and of roots on the other, than that at Lois Weedon. 

But to return. The question is of vital importance to prac- 
tical agriculture, however little it may interest or afiect the 
researches of *' chemists and men of science," — what is the cha- 
racteristic nature of the exhaustion induced by the growth of the 
most important crop of the farm ? And, we may add, — whether 
OT not soils generally, or soils of any particular class, are compe- 
tent, without injury, to sustain an annual extraction of mineral 
constituents, and to liberate, or (either by themselves or by the 
plants growing on them) newly to acquire from the atmos- 

* Journal of Agriculture qf the Highland and Agricultural Society of Scot' 
^d, July 1866. 



16 The Lois Weedon Plan of Growing Wlieat; 

phere, a sufficiency of nitrogen for fall crops, in an available and 
assimilable' form ? 

Certainly, if we were to rely upon the mean resnlts of the 
42 analyses referred to by Baron Liebig (in No. xxxvii. of the 
Journal of the R. A, S.) in illustration of the amount of nitrogen 
contained in soils, we should be led to conclude that many soils, 
at least, had enough of the mineral constituents of oar crops for 
thousands of years, under the ordinary practices of rotation^ and 
for hundreds of years of the growth of wheat on the Lois 
Weedon system. Almost all other published analyses of 
soils would lead to a similar conclusion; in fact, we know of 
scarcely any that would not. It must be freely confessed, how- 
ever, that the methods by which soils have hitherto generally 
been analysed, have proved themselves, in their results, to be little 
fitted to afford the information for which the analyses were 
uudertaken. Nevertheless, judging from the whole of the evi- 
dence of this kind at command, it may perhaps safely be con* 
eluded that, excepting the one constituent phosphoric acid, 
the greater proportion of soils which are termed ** heavy^ 
" clayey y^ or '* loamy ^^^ do contain^ within a workable depth, a 
sufficiency of mineral constituents for thousands, or hundreds, of 
years, as above supposed. It is, however, by no means so clear, 
that many of them would not fall short rather in annual libera^tum 
in available forrrij than in actual percentage amount of the neces- 
sary mineral constituents. Indeed, there is evidence enough 
in agricultural experience to show that, although the ordinary 
practice of rotation leaves, in most soils, a balance of available 
mineral constituents, and therefore demands a supply of nitrogen 
from without, yet, with this supply alone, the point of the re- 
quirement of more immediately available mineral constitaents 
for full and healthy crops is in its turn frequently soon arrived 
at. In fact, it is the '^ condition" both as regards mineral and 
nitrogenous supplies, rather than the actually eadsting amount ot 
them in the soil, that becomes defective. And in the lighter soils 
more especially it is, that the condition as regards the mineral con- 
stituents of our crops, or the floating capital so to speak, both bears 
a much larger proportion to the available stores of the soil itself, 
and is more dependent on restoration or supply from without. 

In Mr. Smith's " heavy land" with its clayey subsoil inter- 
mixed, disintegrated, and well weathered (and perhaps even in 
his *' light land," with its dressing of marl), it is quite clear, 
from the continued good results, that the annually available 
mineral supply, or the mineral condition, is not at present im- 
paired ; nor, so far as existing knowledge of such matters can be 
relied upon at all, need Mr. Smith be alarmed lest the dormant 
stores, at least of his heavy soil, should not last the century 



I 






and^ The combined Nitrogen in Soils, 17 

which, he says, should satisfy living man. And it should be 
borne in mind, that the resources of the soil are not to be spoken 
of, as some are wont to do, as snfiBcient for — say fifty or a hun- 
dred crops, and to be cleared off to the zero point at pleasure, in 
half or doable the number, accordingly as the soil is supplied with 
other elements of growth. Whatever the actual stores of the 
soil, they are only little by little available; and it is not easy to 
suppose that a heavy soil, yielding, under proper management, 
annually enough for large crops over a continuous series of 
years, does not contain a correspondingly enormous store in the 
dormant state. Whether, however, the same soil would annually 
yield an equal supply of available minerals if its surface were 
less exposed to weathering influences, and the required nitrogen 
for fnll crops were provided by manure, is quite another 
qnefltion. 

But now let us turn, as briefly as possible, to a consideration 
of the nature of the evidence which analysis affords of the 
Bmount of nitrogen contained in soils, and then, equally briefly, 
to a review of some of the circumstances which seem to have 
their share in the production of the large annual crops of wheat, 
without manure, at Lois Weedon. 

As is well known, in 1843 Baron Liebig laid more stress than 
formerly on the sufficiency of the assimilable supplies of nitrogen 
m the atmosphere ; and a few years later, after having before 
him the analyses of a number of soils made in his laboratory by 
Br. Krocker, he superadded to the argument of the inexhausti- 
bility of the supplies of the atmosphere, that of the large amount 
of nitrogen contained in soils themselves, to show that little or 
no effect could be attributed to the small proportion which is 
added in an ordinary dressing of manure ; and to this he now 
adds, still more emphatically, in reference to fallow, that the accu- 
mulation of ammonia in the soil in one year has no influence on 
the crop in the sacceeding year. With regard to the amount of 
mtrogen in the soil, we, in 1847, alluded to this point, and gave 
^he percentage obtained by analysis of the surface-soil of the 
field upon which our experiments on wheat were being con- 
ducted. The necessary distinction to be drawn between the im- 
mediately available and the actually existing contents of the soil, 
M above referred to, was, however, too obvious to allow a mo- 
ment's scepticism as to the influence of the small proportions of 
available nitrogen which, in our experiments, we superadded in 
manure. On this point, however, as it is very important to the 
fitfmer that he should be satisfied respecting it, we cannot do 
hetter than quote the replies to this argument of Baron Liebig 
hf M. Boussingault and by M. Kuhlmann ; to the latter of whom 
^aion Liebig dedicates the fuller version of his paper in No. 

B 



18 The Lois Weedon Plan of Growing WhecU ; 

zxxvii. of the Jovrrud of the B, A. S.^ which is published as an 
independent work in Germany. 

M. Boussingault says, — 

" Latterly, M. Liebig has sought to establish that the mineral matters, the 
alkaline salts, are the only efficacious agents of manures, supporting this 
assertion by analyses which indicate in arable land, even when uniiianured,a 
considerable proportion of ammonia; from which it has been concluded that, 
as the soil always contains a more than sufficient amount of nitrogenixed 
matters, there is no necessity to supply them to it.* " 

And further, — 

" This alkali was determined by calcining the soil with a mixture of soda 
and lime. We know that, by this method, the nitrogenized substances are 
transformed into ammonia; but the process does not enable us to decide 
whether this ammonia was entirely formed in the matter examined. In fact, 
a soil might furnish by analysis a very large proportion of the volatile 
alkali, and yet we mig[ht not be justided in affirmwg that it oontaina, I 
will not say this alkali already formed, but eren putrescible nitrogenized 
substances, that b to say, those which are efficacious in Tegetation. TauB we 
might extract from a soil abounding iu peaty debris, from a bituminous 
schist, large quantities of ammonia, without, on that account, being sure of 
obtaining advantageous crops from such soils. 

^* However, it is according to the determinations of nitrogen that M. Liebig 
stAtes that a hectare of araole land, taken to a depth of 25 centimetres, con- 
tains, not the elements of ammonia, but 2000 to 10,000 kilogramznes of 
ammonia itself; a result presented as an objection against the necessity of the 
employment of nitrogenized manures. M. Euhlmann has remarked, with 
reason, that there is an answer to this objection in the facts themselves, and it 
is, that a hectare of land may contain enough of nitrogen held in stable com- 
binations to represent as much as 10,000 kilogrammes of ammonia, and 
nevertheless give meagre crops, whilst, if dressed with 250 kilogrammee of 
ammonia in the form of manure, it will yield, after cultivation, a satisfactory 
produce." t 

* *' Dans ces derniers temps, M. Liebig a cherch6 i^ ^tablir que les matidres 
mineral es.les sels alcalins, sont les seuls agents efflcacesdesengrais, en appuyant 
cette assertion sor des analyses qui indiqneraient dans la terre arable, alors mdme 
qu*elle n'est pas f um^e, une forte proportion d*ammoniaque ; d^oil Ion a condu 
que le sol contenant tou jours une dose plus que snfflsante de mat6riauz azot^ il 
n*y a pas lieu de lui en f oumir.'* — EconaniU RuraU, tome ii. p. 77. 

f ** On a dos6 cet aloali en calcinant la terre avec un melange de sonde et de 
chaux. On salt que, par cette m^thode, les substances azot^es sont trans- 
form^es en ammoniaqne; mais le proc^6 ne permet pasde deciders! cette am- 
moniaque 6tait toute formle dans la mati^ examinee. En effet, une terre 
pourrait foumir k I'analyse une tr^forte proportion d*alGali volatil, sans que 
pour cela on tdX en droit d'affirmer qu*elle contient, je ne venx pas dire cet 
alcali toutoonstltu^, maismdme des substances azotAes putrescibles, o'est-a-dire, 
efficaces dans la v§g6tation. Ainsi, on extrairait d*un sol abondant en d6bzis 
tonrbeux, d*un schiste bitumineux, de fortes quantity d'ammoniaqne, sans que,- 
pour cela, on soit assure de retirer de semblables terrains des r^ooltes avanta- 
geuses. 

" Gependant, o'est d*apr^ des dosages d'azote, que M. Liebig tiouve qu'iin 
hectare de terre arable, sur une profondeur de 25 centimetres, contient, non 
pas les 616mentB de rammoniaqne, mais 2000 k 10,000 kilog. d'ammoniaqne eo 
nature, rteultat pr6sent6 comme une objection oontre la n6ces8it6 de l*inter- 
vention des engrais azotes. M. Kulhmann a fidt remarquer, avec raison, qu'il 
ywkk' oette objection une r^ponse dans les faits mdmes, et c'tft qu*un hectare 



I 



• and, The combined Nitrogen in SoUa. 19 

M. Kahlmann himself says, — 

" Neither must the nitrogen be held in too stable eombinationd, as it exists 
in coal, the direct employment o( which does not conduce to the fertilisation of 
the soil, but which by distillation yields a very fertilising ammoniacal liquid. 
Do not the same reflections apply to au objection raised aj^ainstthe necessity of 
the emplo3rnieDt of nitrogenized manures; namely, that a hectare of land to the 
depth of 20 to 25 centimetres contains ammonia m quantities indnitely greater 
than those by means of which we seek to proyide it with the elements of 
fertility P In my opinion, it is not sufficient that distillation should enable us 
to separate ammonia from the soil ; it is ne jessary that this ammonia should le 
aecessible to the plant without the aid of tire or of other energetic agents. 

" There ia moreoyer a reply to the objections stated above in the facts 
themselyes ; a hectare of land may contain enough of nitrogen held in stable 
eombinations to produce 6000 or even 10,000 kilogi'ammes of ammonia, and 
^et give poor crops. If we apply to the same land 250 kilogrammes of 
ammonia, in the form either of orcnnary manure or of pure ammoniacal salt, 
the fertility will be doubled. 

** A^grictilture is, above all, a science of facts ; it is in experieoce that it 
must seek the basis of its theoretical laws.'* * 

These, then, are the opinions of chemists as well known by 
tkeir investigations in the field as by their researches in the 
laboratory. 

Haying now to record some recent determinations of nitrogen 
in soils made at Rothamsted, it may be well first to dwell for a 
moment on some of the previously published data of this kind 
which have been quoted by Baron Liebig. With regard to the 
determination of nitrogen in soils, made by Dr. Krocker in 
1846, in the Giessen laboratory, it appears, by reference to the 
original paper {Anncden der Chemie und Pharmade, Band 58, 
pp. 381-8), that he only made a single determination on each of 

de tene pent contenir assez d'azote engag^ dans des combinaisons stableH, 
pour repr6senter jasqu'^ 10,000 kilog. d'ammoniaque, et donner n^omoins des 
i^ltea ch6tiyes, tandis que, fam6 avec 250 kilog. d'ammoniaque & I'^tat 
d'engiais, il rendra, par la ci^lture, des produits satisfaisants." — Ibid. p. 78. 

* ** II ne f aut pas non plus que I'azote soit engag6 dans des combinaisons 
tTop stables, comme cela eziste pour la houille, dont Temploi direct ne donne 
pas ilea i la fertilisation du sol, mais dont la distillation d^place un liquide 
^uuDODiacal tr^s-fertilisant. Les mdmes reflexions ne s'appliquent-elles pas k 
^^ objection produite contre la n^oessit^ de Temploi des engrais azot6s ; k 
nvolr qu'un hectare de terre & 20 ou 26 cent im^tres de prof ondeur contient 
des qoantit^s d*ammoniaque infiniment sap^iieuresAcelles au moyendesquelles 
on cherche & lui donner des 616ments de fertility 7 Dans ma pensile, il ne suffit 
pss que la distillation permett^ de d^placer de Tammoniaque de la terre, 11 fant 
que sans le secours du feu ou d'agents 6nergiques cette ammoniaque puisse 
*tro offerte k la plante. 

"U y a d*ailleui8 k Tobjection pr6sent6e ci-dessns une r6ponse dans les faits 
i&dme. Un hectare de terre pent contenir assez d'azote ehgag^ dans des comhi - 
^^^ns stables pour produire 6000 et meme 10,000 kilogrammes d'ammonieque 
et donner oependant des r&ooltes ch^tlves. Si Ton fume cette terre aveo 250 
tiiogiammes d*ammoniaque 4 I'^tat d'engrais ordinaire ou de sel ammoniacal 

V^h la fertility sera donbl6e. 
*' ^'agriculture est, avant tout, une science de faits, c'est dans rexpdrience 

qo'eUe doit chercljer la base de ses lois th^oriques.*' — Annaltft d^ Chimie et de 

%«?««, yol. XX., 1847, p 271. 

B 2 



^ 



20 The Lois Weedon Plan of Qromng WheaJt; 

the soils. We are therefore (though without calling tliein in 
question) unable to form any such judgment from the resnlts 
themselves of the probable limit of error arising from mani- 
pulation and other causes, as duplicate analyses would have 
enabled us to do. And when it is borne in mind, that moat 
of the published analyses show an amount of nitrogen in soils 
only amounting to from one-tenth to one-qaart«r of 1 per cent., 
it will easily be seen that slight errors of analysis, snch as 
in most subjects of investigation would be quite immaterial, 
are here of the utmost consequence — if, at least, we should 
wish to discuss, by the aid of such analyses, such difierenoes 
between soil and soil, or between the same soil in the conditions 
in which it would yield respectively a given amount of crop 
below a usual average, or a full one, equal to twice as mnch as 
the former. In illustration of this, we need only say that 1 OO lbs. 
of ammonia, added to an acre of soil weighing 4,000,000 lbs. 
(and which every intelligent farmer knows would, on most soilfl^ 
increase his crop enormously), would, if well mixed with the 
bulk of soil, only raise its ammonia by 0*0025 per cent. — or 1 
part in 40,000. This fact should not be lost sight of in the 
consideration of the figures which will shortly follow. 

Next to the determinations of nitrogen in soils by Dr. Krocker, 
as referred to above, the most extensive series quoted by Baron 
Liebig is that made at the instance of the Boyal College of Tiund 
Economy in Berlin. Baron Liebig introduces these results as 
follows (and the italics in the second paragraph are his own) : — 

'' The fact of the presence of this enormous amount of nitrogen in the soil 
has heen con6rmed b^ the researches made at the instance of the Royal Oolhn 
of Rural Economy m Berlin (Annalen der LandwirUuchaftj vol. xiv., p. 2). 
The College of Rural Economy caused land of apparently uniform quiJity to 
be selected in fourteen different localities in Prussia for these experiments. 
At ten or twelve different points of each of these fields an equal quanti^ of 
earth was taken by the spade from the entire deptJi of tiiie arable soil; these 
portions, in each case, were thoroughly mixed, and from the mass samples 
were taken. 

'' In each sample the amount of nitrogen was determined hy three different 
ehemisti separately, and from their results have heen odculated for one acre of 
land, to the depth of 1 foot (the specific gravitv of the soil being taken at 1*6), 
™ ,?!?^™fl^ quantities of nitrogen, expressed: however in pounds of ammama 
(17 lbs. of ammonia contain 14 Ihs. of mtrogen).*'-n/(mr. Moy. Ag. 8oc. JSng,^ 
vol. xvu., part 1, p. 286. -^ j^ -▼» 

^ As these determinations are introduced to the reader by so 
high an authority in the matter of chemical analysis, as being 
made ** by three different chemists sepwrately,'' and as Baron Liebig 
arranges the soils in the order of their richness in nitrogen, 
accordmg to the mean of the three experiments for each soil, it 
may be interesting to examine what was the sort of agreement 



and, The combined Nitrogen in Soils, 21 

between the resalts of the three experimenters on each of the 
fourteen soils. Accordingly there is given in Table III., p. 22 : — 
In the upper portion, the percentages of nitrogen in each soil, 
as found by each of the three chemist43, and calcnlated upon the 
soil dried at 100** 0. (210** F.), are given. And— 

In the lower portion of the Table, the calculated lbs. of am- 
monia per acre of 4,000,000 lbs.* of dry soil, according to the 
determinations of each separate experimenter, and also according 
to the mean of the three, are given. And in the last column are 
given the lbs. per acre of ammonia for each soil as calculated by 
; Baron Ldebig. 

; So discrepant are the determinations of the three separate ex- 

I perimenters on the same soil in almost every case, that the results 
must be considered quite inapplicable as a means of arranging 
the soils according to their probable relative amounts of nitrogen. 
So great, indeed, is the discrepancy, that we find frequently once 
and a half or twice as much, and in several instances even ten 
times as much, recorded by one chemist as by another, for one 
• and the same soil. In &ct, in applying each of the separate 
f analyses instead of the mean of the three, to estimate the amount 
of nitrogen or ammonia per acre, we find that one or two of the 
soils conld be put both at the top and nearly at the bottom of 
Baron Liebig's list, accordingly as we select the determination 
of one or another of the experimenters ; whilst in the same way, 
aeveral others might be separated from one another by half the 
items in the list. It may even be a question, how far a judg- 
ment can be formed from such results of the probable average 
or range of amount of nitrogen in the soils. 

It is, however, only due to Professor Magnus, the able and 
conscientious reporter to the Royal College of Rural Economy m 
Berlin, of the analyses in which these nitrogen determinations 
are but items, to say that he called particular attention to the 
little agreement between the results of the difierent experi- 
menters. In fiwjt, his chief conclusion was, that as twenty-one 
of the best chemists in Germany, or of those working under the 
snperintendence of the most distinguished chemists, had been 
selected, and as there conld therefore be no want of technical 
knowledge devoted to the subject, it was obvious that in the 
existing state of science little was to be expected from the 
analysis of soils. 

* The estimate of 4,000,000 lbs. of dry soil per acre, taken to the depth of 
one foot, is higher than we have been accnstomed to take it ; but we adopt it 
bere, not only becanse it is a convenient round number, but because it obviously 
agrees very closely with the amount supposed by Baron Liebig, with whose 
estimates we are comparing our own figures. It is obvious tliat the cubic con- 
tents, and the weight of availcMe soil on an acre, must vary extremely ; so 
that any figure adopted in an estimate of this kind must be to a great extent 
Mbitraiy. 



22 



Tlie Lois Weedon Plan of Grooving Wheat ; 



Tablk III.— Showing the Percentage of Nitrogen, and the supposed Ammopia 
per Acre calculated therefrom, in 14 Soils, each Analysed by tbree Chemists 
separately. 



Nitrogen per Gent, in the Soils. 



1. Havixbec 

2. Burg Wegeleben 
8. Turgairschen ... 

4. WoUup 

6. Beesdau 

6. Turwe 

7. Dalheim 

8. Laasan 



• • • • • • 



9 Eldena 

10. Burg Bornbeim 

11. Neuensnnd ... 

12. Frankenfelde ... 

13. Neuhof 

14. Cartlow 



By 

lilt 

Experimenter 



3ud 
Experimenter 



By 
Experimenter 



{ 



0-591 
0-432 
0*240 
0-200 
0137 
0140 
1-609 
0112 
0090 
0-120 
0102 
0147 
0079 
0130 
0-076 



} 



0-081 

0-350 
0-298 
249 
0130 
0150 
0113 

0120 

0-114 
0103 

0-164 
0106 



0-400 
0-270 
0-280 
0-271 
0108 
0173 

0-138 

0-113 

0113 
0010 
0-093 
0011 
0005 



0-3.57 
0-351 
0-290 
0-256 
0165 
0-148 
0-879 
0121 

0-111 

0-110 
0H)87 
0-086 
098 
0-062 



Nitrogen calculated as lbs. of Ammonia per Acre of 4,000,000 lbs. of "Dry Soil 



1 










Ammonia 


1 


1 

By By 

Ist Snd 

Experimenter 1 Experimenter 


By 

8rd 
Experimenter 


Mean. 


inilML 

per Acre 

1 foot deep, 

as given 












hyUMg. 


1. Havixbec 


28,704 


3,932 


19,428 


17,352 


18,040 


2. Burg Wegeleben 


20,980 


• •  


1H,112 


17,048 


17,200 


3. Tur^itschen ... 


11,660 


17,000 


13,600 


14,084 


14,350 


4. Wollup 


9,713 


14,472 


13,160 


12,448 


13,120 


6. Beesdau 


6,652 


12,092 


5,244 


7,999 


7,790 


6. Turwe 


6,800 


6,312 


8,400 


7.172 


7,380 


7. Dalheim 


78.151 


7,284 


• • • 


42,716 


6,970 


8. Laasan 


5,440 


5.488 


6,702 


5,877 


6.740 


9. EldcDa 


/ 4,371 
\ 5,828 


1 6,8:8 


5,488 


6,377 


5,330 


10. Burg Bornheim 


4,954 


6,537 


5.488 


6,328 


5,330 


11. Neuensand 


7,140 


5,002 


485 


4.211 


4,610 


12. Fiankenfelde... 


8,837 


• • • 


4 517 


4,120 


4,100 


13. Neuhof 


6,312 


7,480 


534 


4.774 


4,V20 


14. Carl low 


3,691 


5,148 


243 


3,026 


2,870 



Concarring fully with Professor Magnus on this point, and 
believing that little advance will be made without previous 
special investigation and adaptation of methods of analysis to 
this particular subject, it is only with the reservation which such 
a conviction implies, that we would now record or apply the 
determinations of nitrogen in soils recently made at Rothamsted 



andy The combined Nitrogen in Soils. 23 

by the current methods. We may say, however, that every pre- 
caution has been taken to secure as much of accuracy as those 
methods are capable of. Nor are we wanting in evidence in the 
results themselves, that within certain limits, and for the discus- 
sion of some points of comparatively broad distinction, they 
are sufficiently conclusive. 

In the following Table (IV.) are given the results of determi- 
nations of nitrogen — in the soil and subsoil of the plot devoted at 
Bothamsted to the experiments on the Lois Weedon system — in 
the soil of the continuously unmanured plot, of the continuously 
mineral-manured plot, of the continuoi;/sly ammonia-manured 
plot, and of the continuously mineral and ammonia-manured 
plot, in the adjoining experimental wheat-field. There are also 
given, the determinations of nitrogen in specimens of soil and 
subsoil, &c., from the Rev. Mr. Smith's experimental fields at 
Lois Weedon. And, for the sake of comparison with the figures 
in Table III. last discussed, there is given in the lower portion 
of the Table (IV.), the amounts of nitrogen (in lbs.) that would 
be contained in 4,000,000 lbs. (=an acre about a foot deep) of 
the specimens analysed — both according to the individual 
analyses, and to the mean result for each specimen. In the last 
column, the mean acreage amount of nitrogen is represented in 
its equivalent amount of ammonia. It is. obvious, however, that 
no actual fact is represented by thus applying the analyses of 
soils and subsoils indiscriminately, to a supposed equal acreage 
weight of soil in each case. The figures are only useful as con- 
veying a very general comparative idea, of about how much 
ammonia, or its equivalent of nitrogen, would exist in a layer of 
one acre area, and about a foot thick, of soils or subsoils contain- 
ing a given percentage amount. 

It must be remarked, too, that whilst the specimens of sur- 
face-soils at Rothamsted were each taken at eight different 
places, and as hearly as possible to a depth of nine inches and 
an area of a foot square, the whole being then well mixed and 
re-sampled, those at Lois Weedon were each taken at one spot 
only ; a good spit of depth being the only condition attended to. 
T\ie soils at both places were collected during the present year 
(1856) ; those at Lois Weedon in August, and most of those at 
Rothamsted in September. 

In all cases the soils were broken up and turned over and the 
Ittrge stones picked out ; they were then further reduced and 
separated from smaller stones. Finally, they were rubbed to 
fine powder and passed through a fine sieve, in which state 
they were submitted to analysis. In these processes of prepara- 
tion the soils were never submitted to a temperature above 60** 
to 70° F., and when so prepared they generally retained less, or 



24 



The LaU Weedan Han of Growing Wheat; 



Tablm IY. — Showing the amonntfl of Nitxogen (ezdnaiTe of Mitoc Add) in 

and LoiB Weedon Soils and Subsoils. 



Nitrogen per Cent, in the Soils, fislcnhitfd as D17. 



Bothamsted 



BnrfaoeSoils, 
adjoining 
Kzperi- 
mental Field 



Lois-Weedon-Plot 1 

Surface Soil ... 1 

Lois-Weedon-Plot 1 

, Subsoil ) 

Botbamfted / Unmanared 

Mineral Manure... 
Ammonia-0alt8 ... 
Minerals and Am- 1 
> moQia-flalts ... i 



1 

Espoi- 
ment 

I. 


EziMri. 
HMOt 

a. 


Expcri- 

9. 


Expcri. 1 


0-1416 


0-1418 


• •• 


• •B 


OK)730 


0-0763 


• • • 


... 


01660 
0-1430 
0-1630 


0-1450 
0-1629 
0-1694 


0-1660 
0-1420 
0-1620 


• •• 

0-1606 


0-1620 


0-1693 


0-1646 


0-1667 



0-1417 

00746 

0-1523 
01459 
0-1687 

0-1666 



.1 

11 

I 

!l 



« Heavy Land Stubble 

HeaTj Land Fallow 

Light Land Fallow 

Heavy Iiand Subsoil 

T^- Wo-jiy*«/ Light Land Subsoil 
LoisWeedon^^^jpj^ ^ 

Light Land Field 
Rye-grass Subsoil, 
with liquid manure 
Heavy Land Field 



} 



01640 


0-1690 


01670 


0-1666 


0-1641 


0-2020 


0-1940 


0*2000 


0-2090 


0-2012 


0-1630 


0-1620 


0-1610 


01640 


0-1660 


0-0661 


00670 


0-0667 


0O610 


0H)662 


0K)840 


00770 


0-0760 


0-0760 


0-0782 


0-0920 


0-0890 


••■ 


••• 


0-0906 

 


00790 


00790 


•■• 


•■■ 


OK)790 



Nitrogen per Acre about 1 foot deep— taken at 4,000,000 lbs. Dry SoU. 



Bothamsted 

Bothamsted 
SurfaceSoils, 
adjoining 
Experi- 
mental Field 



^Lo*8-Weedon-Plot » 

Surface Soil ... i 

Lois-Weedon-Plot ) 

Subsoil 1 

I Dnmanured 

Mineral Manure... 

Ammonia-salts ... 

Minerals and Am- 1 

V monia-salts ... ; 



Experi- 
ment 
1. 


Ezperi- 

meat 

2. 


Expert- 

meat 

3. 


Experi- 
ment 

4. 


Meftn. 


ItM. 


Ibe. 


lbs. 


lbs. 


Ib«. 


6,664 


6,672 


••• 


*•• 


6,668 


2,920 


3,052 


••• 


••• 


2,984 


6,240 
6,720 
6,120 


6,800 
6,116 
6.776 


6,240 
5680 
6.480 


6,020 


6,092 
5,836 
6,848 


6,080 


6,372 


6,180 


6,268 


6,224 



liM. 



i,ouOjDOona 

6,8IS 

3,623 

7^7 
7,«6 
7,W 

7^r 



Heavy Land Stubble 
Heavy Land Fallow 
Light Land Fallow 
Heavy Land Subsoil 

T^i- w-.-i*?«« /Light Land Subsoil 
Lois Weedon xj^^jp.^ 

Light Land Field ) 
Hye-grass Subsoil, 
with liquid manure 
Heavy Land Field 



1 6,560 


6,360 


6.680 


6.664 


6.664 


; 8.080 


7.760 


8.000 


8,360 


8,048 


6,620 


6,080 


6,040 


6,160 


6,200 


1 2,644 


2,680 


2.668 


2,440 


2,608 


3,360 


3,080 


3,040 


8,040 


3,128 


3,680 


3,560 


••• 


••• 


8,620 


i 3,160 


3,160 


••• 


•• • 


8,160 



7,970 

7,628 
ai68 

4,8)6 



and^ The combined Nitrogen in Soils. 25 

little more, than 5 per cent* of water separable by farther drying 
at 212^. For convenience and uniformity, the determinations 
in the Table are all given as calculated upon the soil so dried at 
212^ ; though separate portions were always employed for the 
determination of the moisture in this way, and those of the 
nitrc^en ^were always made upon the partially and only air-dried 
snbetance. 

The nitro^n determinations were made by burning with soda- 
lime, coUectini; the ammonia in hydrochloric acid, and estimating 
as platinum salt in the usual way. It is obvious that this 
method does not give that portion of nitrogen which may exist 
as nitric acid. But from the interesting results of Professor 
Way, on the power of soils to absorb ammonia and nitric 
acid respectively, and on the general relation of these two sub- 
stances in drainage-water, it may perhaps safely be concluded 
that, in most ordinary soils, but a very small proportion of their 
contents of nitrogen will be retained as nitric add. 

The two, three, or more determinations upon each soil were 
m only one or two cases made by the same analyst ; two persons 
being employed upon the series, each, as a rule, making two 
determinations upon the same specimen. In this way it was 
hoped to eliminate any prevailing tendency to high or to low 
results which might attach to the work of either operator. It is 
probable it would be the opinion of most chemists, that the dis- 
crepancies in the percentage amounts of nitrogen which the Table 
^shibits are neither greater nor more numerous than were to be 
expected in the manipulation of the process employed, by two 
operators on such a series. When, however, it is remembered 
that, as already pointed out, the large dressing of a hundred 
pounds of nitrogen per acre, distributed through the soil to the 
depth of 1 foot, would only raise its percentage of nitrogen by 
00025, equal ^^ioo ^^ of its weight, it would at once be seen, 
that the separate determinations on the same soil frequently, 
^Vy generally, differ much more from each other than would the 
^nal soil before and after such a potent manuring. It is clear 
then from this simple illustration, that such methods of estimat- 
^g the nitrogen in soils are quite inapplicable to determine the 
difference in this respect between a soil yielding 16 bushels of 
^heat without manure, or twice, or twice and a half the amount, 
^th it. That is to say, such methods are quite incompetent 
adequately to treat the question of the mere temporwry '* condir 
tf<m " of soils. 

Exercising, then, all due caution, on the score both of the 
difficulty of fairly and uniformly sampling soils for analysis, and 
^'f that of accurately determining the nitrogen by current methods, 
lebns see what are some of the more general indications of the 



26 The Lois Weedon Plan of Orowing Wlteat ; 

Table. For this purpose we take of conrse the mean results 
instead of the separate determinations ; which latter, however, 
although disagreeing with each other sufficiently to show that- 
the figures could not be relied upon to treat of the nice question 
of the effect of a single even heavy dressing of manure, hav^e 
still so much of agreement, as to give some confidence at least in 
the direction^ and in any marked distinctions, which the mean 
results would indicate as between soil and soil. 

It is seen that the subsoils contain from one-half to one-third 
only as much nitrogen as the surface soils. From this it is 
obvious that an inch or two of variation in depth, in sampling s 
surface soil, might make a comparatively important difference in 
the percentage of nitrogen obtained. The effect of the admix- 
ture of more or less of subsoil, in a sample of professedly surface 
soil, is seen in the difference between the mean percentage in 
the Bothamsted soil which had been cultivated on the Lois 
Weedon plan, and that of a similar description in the adjoining 
field, which had grown wheat for several successive years, but 
without its subsoil being disturbed. Thus the trenched plot at 
Kothamsted gives a mean percentage of only 0*1417 of nitrogen, 
whilst the plot in the adjoining field, notwithstanding it has 
grown wheat for many years successively without manure, gives 
01 523 per cent. 

Before proceeding to compare with one another the Rotham- 
sted and the Lois Weedon soils, we may here, in passing, call 
attention to the fact that, slight as they are, and whether acci- 
dental or not, the differences which the mean results would 
show between the plots devoted to. the continuous growth of 
wheat at Bothamsted, under different conditions of manuring, 
are really, at least in direction, such as those manuring condi- 
tions would lead us to expect. Without laying too much stress 
on the actual figures, it is seen, then, that whilst the continuously 
unmanured plot gives 0-1523 per cent, of nitrogen, that which 
has received for a series of years mineral manure only (which 
would tend to the extraction of more nitrogen from the soil than 
where no manure was employed) gives 0*1459 per cent., or 
rather less than the former. The plot which has received 
annually ammonia-salts (as the results showed somewhat; in 
excess of the available minerals), indicates 0-1587 per cent, of 
nitrogen ; or rather more than either the continuously unmanured 
or the continuously mineral-manured plot. And again, quite 
conformably with the above, the plot which has received con- 
tmuously both mineral manure and an excess of ammonia- 
salts, shows a slightly lower percentage (0-1556) than where the 
ammonia-salts were employed without minerals ; though with 
this excess of ammonia-salts, a slightly higher one than the 



and, The combined Nitrogen in Soils. 27 

tminanQred plot. Thus in both instances where a liberal supply 

of minerals Has been nsed, the effect of which would be to use 

up, 8o to speak, more of the available nitrogen within the soil, 

the mean percentage of nitrogen indicated was rather lower 

than in the cases comparable with them on this point. It is 

freely granted, that some of the individual determinations are 

not quite consistent with the conditions here supposed; yet, 

with three or four experiments in each case, agreeing as most of 

.them do pretty nearly, it is really of interest to observe, that 

the mean results appear to bear some relation to the known 

history of the plots. 

Taming now to the Lois Weedon soils, it is seen that both 
specimens taken from the heavy-land field show a higher per- 
centage of nitrogen than any of the Bothamsted plots, and par- 
ticxilaTly higher than the specially comparable instance at Roth- 
amsted ; namely, that where the land had been trenched and 
some of the subsoil intermixed with the surface soil. The Lois 
Weedon light land even, gives a slightly, but very slightly, 
Vugher percentage of nitrogen than the surface^soil of the con- 
tinaoasly nnmanured plot at Bothamsted. The difference, 
however, in favour of the Lois Weedon light land, notwith- 
standing it had been intermixed with subsoil and with marl, 
each containing only about half as much nitrogen, is more 
marked when it is compared with the trenched, that is, 
the Lois Weedon subeoiled plot at Bothamsted. To go to 
figures, we find that whilst the mean of four analyses gives for 
the Lois Weedon heavy-land stubble 0*1646 per cent, of nitro- 
gen, the mean, also of four analyses, gives for the heavy-land 
fiUUnv 0*2012 per cent. We cannot at all suppose that the 
vhole of this large difference, amounting, as it would do, to 
from 1000 lbs. to 1500 lbs. per acre, if reckoned at about 1 foot 
deep, is due solely to the joint influence of the exhaustion of the 
just removed crop in the one case, and to the accumulation by 
the tilled bare fallow in the other ; though it is obvious, that 
the effect of the accumulation by fallow would not extend uni- 
formly to the depth of 1 foot ; and consequently the assumption 
^^ a gain of 1000 lbs. or 1500 lbs. of nitrogen per acre is very 
much higher than the figures really imply, even supposing the 
^tuples were really taken to exactly corresponding depths in 
the two cases. The more probable supposition is, however, that 
the sample taken from the stubble did in fact represent a some- 
what greater depth of the staple, or more of intermixed subsoil, 
^han that taken from the fallow interval. 

Taming for a moment to the subsoils and marl, the Rotham'- 
^Mi unexposed subsoil indicates a rather higher percentage of 
nitrogen than the Lois Weedon heavy-land subsoil — the former 



2b The Lais Weedon Plan of Qrawing Wheat ; 

giving 0*0746 and the latter 0*0652 per cent. It is seen, on the 
other hand, that the subsoil and marl of the Lois Weedon light- 
land field, with which the surface-soil is intermixed, both give a 
higher percentage than either the Bothamsted or the Ix>is Wee- 
don heavy-land subsoil — that of the light-land subsoil being 
0-0782, and that of the marl 0'0905 per cent. Lastly on this 
point, whilst the subsoil of the Lois Weedon heavy-land un- 
manured wheat-plot gives 00652 per cent., the subsoil of the 
plot devoted to rye-grass, with liquid manure, in the same field, 
gives 00790 per cent. 

To resume — the comparison of the percentage of nitrogen in 
the Lois Weedon and the Rothamsted soils submitted to Mr. 
Smith's methods of growing wheat, the one with so much success, 
and the other with such signal failure, shows that the former 
contain a higher percentage of nitrogen than the latter. Thus, 
whilst the mean percentage in the trenched plot at Bothamsted 
is 0*1417, that in the light-land at Lois Weedon is 0*1550 per 
cent., and in the heavy-land at Lois Weedon (taking the mean 
of the eight determinations on both stubble and fallow plots) is 
0*1827. Independently, then, of mere physical condition of 
soil, of mineral richness, or of other circumstances affecting^ the 
relations of the plant to the soil, we have here an intellig'ible 
chemical difference, perfectly consistent with what all other 
experience regarding the requirements for the vigorous growtb 
of the wheat-crop would lead us to anticipate. 

The questions still remain, however, whether the Lois Weedon 
soils, in all probability, have a greater power to acquire nitrogen- 
ous plant-food from atmospheric sources, or are likely more 
lightly to retain, or more easily to give up to the plant in an as- 
similable form, their previously existing or newly-accumulated 
stores of nitrogen ? 

With a view of getting such indications on these points as 
limited time would permit, the following experiments were made. 
Bather more than one thousand grains, in a finely-powdered state, 
of each of the soils enumerated in the Table (V.) given below 
(whose nitrogen had previously been determined), were put into 
a water-bath for about six hours, in order to secure an equal 
state of dryness. Exactly one thousand grains of each were then 
weighed and respectively placed in small but equal-sized basins. 
Each of these was then mounted upon a small porcelain pot an 
inch and a half in height, and so placed in a large glass basin 
containing water to the depth of about an inch. The large basin 
was then covered with another such, and the whole left for three 
days at a temperature of 100** or more ; by which from 1^ to 
nearly 4 per cent, only of water was absorbed by the diflferent 
soils. The water in the large basin was then replaced by pretty 



f 



and, The combined Nitrogen in SoUt. 



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30 The Lois Weedon Plan of Growing Wheat ; 

strong ammonia- water ; and the whole, covered as before, was 
left for fonr days in a warm room, the temperature being main- 
tained at about 70°. Even now none of the soils had gained 
quite 5 per cent, of water ; and as it was thought that the absorp- 
tion of ammonia would be facilitated thereby, 5 per cent, was 
now added to each of them ; and after another four days' expo- 
sure to the moist ammoniacal atmosphere, a further 10 per cent, 
of water was added. In four days more the little basins were 
removed from the ammoniacal atmosphere, and by this time the 
soils smelt very strongly of ammonia. In order to expel all 
that was not retained in a comparatively stable condition, the 
little basins and their contents, uncovered, were exposed for 
eighteen hours in the warm room at about 70° ; by which, as will 
be seen in the Table, the amount of moisture was reduced in 
all cases to below 3, and in some to below 2 per cent. In this 
state the percentage of nitrogen was again determined in the 
soils by the soda-lime and platinum-salt process; and in the 
Table are given the results of these determinations ; and by their 
side, the mean percentage of nitrogen in the respective soils 
before they were submitted to the ammoniacal vapours. The 
percentages of water in the specimens at the different stages, as 
above described, and the percentage gain of nitrogen by absorp- 
tion, calculated both upon the dry soils and upon the previously 
existing nitrogen in them, are also given ; the former to the left, 
and the latter to the right of the nitrogen determinations. 

A glance at the Table shows that there is some general though 
not numerically exact connexion between the capacity of tihe 
different soils for the absorption and retention of water on the 
one hand, and of ammonia on the other. It is seen that the Lois 
Weedon heavy land and its subsoil absorbed and retained a very 
much larger proportion both of water and ammonia than either 
the Rothamsted soil, or the Lois Weedon light land, or light- 
land subsoil. Thus the nitrogen in the Lois Weedon heavy 
land, which was before the highest in the series, has been raised 
by the absorption experiment by 0*1925 per cent. ; whilst that in 
the Rothamsted soil is raised by only 0*1306. The Lois Weedon 
light land has, however, absorbed, or at least retained, less of 
ammonia than the Rothamsted soil, the increased amount of 
nitrogen in its case being 00988 per cent. It is further seen 
that both of the Lois Weedon subsoils have absorbed more than 
their corresponding surface soils; the increased percentage of 
nitrogen by absorption of ammonia being in the heavy-land sub- 
soil 0-2292, and in the light-land subsoU 0*1109 per cent. 

It was our intention, had time permitted, to have completed 
other experiments of this kind for the purposes of this paper ; 
and we may possibly yet be able before concluding to append 



and, TJie combined Nitrogen in Soils. 31 

the results of some such which are liow in progress. In defect 
of these, however, we cannot fail to observe as a significant fact, 
that the Liois Weedon heavy land, which has yielded Mr. Smith 
his best results, both contained more nitrogen in its original 
state, and absorbed and retained, under equal circumstances, both 
more water and more ammonia than the Rothamsted soil. The 
Lois Weedon light land, however, although containing slightly 
more nitrogen in its natural state than the soil at Rothamsted, 
absorbed and retained, in the experiment above described, rather 
le^ both of w^ater and of ammonia than the Rothamsted soil. 
In drawing any conclusion from the results of an experiment of 
this kind, in regard to the probable comparative qualities of the 
soils in their natural state and position, we must first carefully 
consider what are the circumstances, in a necessarily artificial 
experiment, which might vitiate a strict comparison of the 
figures. It is to be borne in mind then, that the soils, when sub- 
initted to the absorption experiments, were in an equally finely 
dirided state, and they would, therefore, expose nearly equal 
STir&ces to the watery and ammoniacal vapours. The results 
eiiould, therefore, show the comparative absorptive powers of 
equal surfaces of the respective soils. And this being so, of the 
three surface soils the Lois Weedon heavy land has the highest, 
the Rothamsted soil the next, and the Lois Weedon light land 
the least absorbent power in relation to a given surface exposed. 
But in its natural state and position the Lois Weedon light land 
ifould undoubtedly expose a much greater surface of atmos- 
pheric influences than the Rothamsted soil. Hence probably 
the reason that the Lois Weedon light land, though it did not 
absorb more ammonia in the experiment cited, yet in its natural 
state contained a higher percentage of nitrogen than the Roth- 
amsted soil. Hence probably also, this Lois Weedon light land 
would both absorb or otherwise accumulate more nitrogen in an 
available form, under equal climatic circumstances, and yield it' 
up more readily to the plant, than the soU at Rothamsted. 

Since the above was in type, the additional experiments 
t^ferred to have been concluded, and we give here a short state- 
iQent of the results. In this second series of absorption experi 
^ents, the object was to include the surface and subsoU of the 
land devoted to the Lois Weedon experiments at Rothamsted ; 
And also to submit the soils in a rather moister state to the 
Ai&moniacal vapours. 800 grains, in an equal state of dryness, 
of each of the soils enumerated in the Table below, had 25 
BBptems, or about 23 per cent., of water added to them. In 
this state they were submitted, in the same manner as in the 
¥^ouB experiment, to moist ammoniacal vapours at a tempera- 



32 The Lata 

tare of about 70° ; t 
of 12 as formerly, 
each little basin of « 
warm room at 60° to 
pnt into closed bott 
takeo for the detera 
and separate portioi 
being in each case m 
ing are the results :- 

Tabi^ yi.—BeBolU of farther B 



Doiiription of UiB SotU. 



(Contiaaooalj nn- 
mannred 
Lois- Weedoa- Plot 
Boila ..."l Surface SoU ... 
Lois-WeedoQ-Plot 

*■ Subsoil 

T t f Heavy Laod Sur- 

W^on '^^^ 

S^« jLifThe Lard Snr- 



The soils being thi 
it seems tiiey did no 
room ; nor were the d 
circnmstances so grei 
conformably with th< 
land retained more wi 
either of the Rotham 
retains more than eitl 
the surface soil that 
relation to the one wh 
as might be expected 
to that of ammonia. 

With regard to the 
resnlts of this second i 
with those of the firs 
the more so, from the 
tion, since the circa 
equally varied. We i 



€Mhdy The combined Nitrogen in SoUs. 3S 

land absorbed and retained more ammonia than the Rothamsted 
soils, and the latter more than the Lois Weedon light land. 
And, as 'was the case with the Lois Weedon soils and their 
respective siibsoils, the Rothamsted snbsoil absorbed and retained 
more ammonia than its surface soil ; and conformably with the 
greater power in this respect of the subsoil, we find the trenched 
land at Rothamgted absorbed and retained rather more ammonia 
than the one which had not had any of its subsoil intermixed 
with it. 

In fact, the results of this second series of absorption experi- 
ments confirm so entirely the bearings of the former one on all 
essential points, that the arguments and conclusions already 
recorded do not require any modification or correction from this 
additional evidence. 

The result of the comparative examination in the laboratory 

of the Liois Weedon and the Rothamsted soils clearly brings out 

the fiM^t, that of the former, the heavy one at least, both contained 

more nitrogen in some form, and had the power of absorbing 

more ammonia under equal circumstances, than the latter ; 

whilst the experiments in the field have shown, that a much 

greater porosi^, and consequently a greater amount of surface 

for atmospheric influences, is attained in this more highly nitro- 

genona, and more powerfully absorbent heavy soil at Lois 

Weedon, than, by an equal expenditure of mechanical means, 

oonld be attained in the one at Rothamsted. The Lois Weedon 

light land, too, certainly contained more nitrogen than the 

Bothamsted soil in its natural state; and, as we have seen, 

would in that same state, in all probability, acquire more under 

equal climatic circumstances, and yield up more in a given time 

to the growing crop. 

It would be taking a very narrow view of the case to suppose, 

ihat no other circumstances than an increased supply of nitrogen 

within the soil have had their share in the success of the wheat 

crop at Lois Weedon. There is no doubt that the methods there 

(ulopted are well fitted to develop to the highest degree the 

Withy distribution of both the underground and above-ground 

feeders of the plant. Those methods favour also the liberation, 

^e elaboration, and the distribution throughout the root-search-^ 

ing area of the plant, of the mineral food of the crop, in a 

manner that it would be impossible to emulate in the application 

of direct manures. This system, moreover, independently of the 

Baere amount of available nitrogen provided within the soil by 

its means, secures also, better than any other means could do, 

the perfect distribution of the assimilable nitrogenous, wherever 

there is a liberal supply of the assimilable mineral food. It so 

G 



^ 



34 T/ie Lois Weedon Plan of Orounng Whtat ; 



happens too, that it is jost those soils which are known id 
possess generally the greatest absorptive and retentive powers, 
that have generally also the greatest stores of most of the 
necessary mineral constituents of our crops. It is not, however, 
all which possess these physical or chemical powers of snrfaoe, 
and these inherent mineral riches, that will allow, with equal 
ease, the exposure of an equal surface for the development and 
available activity of these powers and stores. 

That the nitrogen shown to exist in soils by the methods of 
analysis which have generally been adopted, does not necessarily 
so exist in a form readily and within a limited period assimilable 
by plants, is easily demonstrable. Thus, with a view to this 
point, several of the soils which have been the subject of this 
paper were operated upon as follows. A given weight (100 
gT*ains) was put into a flask, 20 ounces of water added, and a 
little strong caustic potash ley. The flask was then connected 
by a tube with a Liebig's condenser, and heat applied so as to 
keep the mixture gently boiling. A series of smaller flasks, 
gauged and marked to hold exactly 4 ounces each, were then 
successively attached as receivers, until three separate fifths of 
the original bulk of fluid had been collected. It has been shown 
by Boussingault, that when very dilute solutions of ammonia <x 
ammonia-salt are distilled in this way, practically the whole 
of the ammonia will come over in the first two-fifths of the 
distillate. And it is obvious that boiling a soil in a fine state of 
division with dilute caustic potash for two or three hours, would 
liberate a very much larger proportion of its nitrogen in the form 
of ammonia than could be rendered soluble and available for 
plants in many years of the influence of air and moisture upon a 
soil in the very limited state of division in which it exists in 
cultivated land. Collecting, however, a distillate of three 
separate fifths, super-saturatmg each with a known quantity of 
a test acid, adding litmus, and then neutralising by a test 
alkaline solution, it was found that only a small proportion of 
the nitrogen existing in the soil (the quantity varying slightly 
with the rapidity of the distillation) was obtained in the dis* 
tillates. And quite conformably with the point established by 
Boussingault, and confirmed in our own experiments in the case 
of rain-waters, the first fifth contained by far the larger proper* 
tion of the whole ammonia which came over ; the third fifbh, in 
fact, containing very little. It was, however, found, that a very 
much larger proportion of the total nitrogen distilled over as 
ammonia from the soils after they had been submitted to ammo* 
niacal vapours as above described, than before they had been so 
treated. 
. Alth0ngh, therefore, it may generally happen that, a soil which 



nndy The conibined Nitrogen in Soils, 85' 

eontains the highest per cent, of nitrogen may have a greater 
aptitade, if w^ell worked, both to acquire more and to yield up 
its accnmalated stores, and hence, so far, be more fertile, yet it is 
obviously quite inadmissible to suppose, that the addition of a 
oomparatively small amount of nitrogen to the soil, in a form 
proved to be readily accessible, can be of no avail, simply because 
the soil itself already contains a much larger absolute amount ; — 
though, from its distribution and state of combination, it may 
be but in very small proportion available within a single season. 
That soils are not necesscurily more fertile because they contain a 
larger actual amount of nitrogen, is interestingly illustrated in 
the efiTects of burning clays. The burnt clay after some exposure, 
as has been shown by Professor Voelcker, contains a much leas 
percentage of nitrogen than the unburn t. No doubt the in- 
creased supply of available mineral food, as well as the change 
of texture by which the roots of the plant, as well as the atmo-» 
sphere, are enabled better to permeate the soil, have much to do 
with the result. That this is so, may indeed be judged, by a 
consideration of the descriptions of crop grown with most advan- 
tage after the burning process. There can be little doubt, how- 
ever, that the smaller amount of combined nitrogen, newly 
acquired by the porous burnt soil, will be much more accessible 
to the plant than the larger amount locked up in the unbnmt 
clay ; and to this circumstance, in all probability, a fair share of 
the beneficial effects of burning should be attributed. In fact, 
this smaller amount of accessible nitrogen in the exposed burnt 
clay, has a much greater proportional effect as compared with 
that in the unbumt, just as the smaller amount added in manure 
in an available form has a striking effect in an ordinary soil, 
notwithstanding that the latter may contain an ^lormously lai'ger 
amount, but in a less accessible condition. 

It is further, we think, very doubtful whether ordinary agricuU 
iurally cultivated soils even contain^ in any form, so large aa 
amount of nitrogen as the uncritical reader might be led to sup- 
pose from the statements on this point given by Baron Liebig in 
the last number of this Journal. The percentages given in soils 
ty Dr. Krocker, whose figures Baron LieWg does not quote 
in the Paper referred to, agree very closely in range with our 
own experience in such matters.* Of those which be has now 
brought more prominently forward, and which we have quoted 
in full at an earlier page, the range is in some cases so high, and 
the discrepancies between the individual analyses of the same 
soil, as already shown, so great, that we are disposed to place 

• Dr. Krocker*8 results will be found in the Appendix to Baron Liebig's 4th 
BngUah Edition of his ChenUttry in its Ap^Uoationt to AgriouUure cmd Phy^ 
^^Vf P- 275. 



86 The,L<n8 Weed<m Plan of Orowiiig Wh^ 

much more confidence in the medinm amonnts given in fliii 
Table. Then, again, neither the Russian black earth, nor the 
soils of gardens or woods (the latter being the only ones given by 
Baron Liebig as analysed by himself), can be taken as paralld 
with ordinary farming-land, nnder ordinary cultivation. 

With regard to any estimates that might be made firom oar 
own determinations of nitrogen in the so3s at Bothamsted and 
Lois Weedon, of the probable acreage amount within a given 
depth, it maybe observed, that the result obtained and published 
ten years ago of the amount of nitrogen in the soil of oar con* 
tinuously unmanured wheat plot (0*2 p.c), was oonaiderably 
higher than that now recorded in Table IV. This was to a great 
extent due to the fact, that the earlier sample was taken to little 
more than half the depth of the recent one. By reference to the 
analysis book we also find that, for a substance containing so small 
an amount of nitrogen, much too small a quantity was submitted to 
analysis. There is also the consideration, whether or not part of 
the difference is due to the reduction of the condition of the land in 
regard to nitrogen, by the removal of ten more unmanured wheat 
crops. Itis clear, however, thatthe determination of nitrogen made 
upon a sample taken to only half that depth, oannot be taken in 
estimating the probable acreage amount to the depth of onefoott 
Then, again, since the analyses now recorded were made npoa 
samples taken to the depth of only nine inches, the calculated 
acreage amounts one foot deep, given in the lower part of 
Table IV. for comparison with Baron Liebig's adopted depth ot 
one foot, must obviously be too high. With these explanations^ 
then, as to the degree of applicability of our figures to any esti- 
mates of acreage amounts, the results are committed to the reader, 
as some additional data on the many points of interest which this 
question of the nitrogen in soils involves. 

It was our hope and intention, had our time permitted it, to 
have included within the limits of this paper a short review oC 
existing knowledge, and especially of the results and tendency 
of the investigations of recent times, bearing upon the sources of 
available nitrogen to cultivated plants, both within and without 
the soil. It is, indeed, remarkable how many are the inde- 
pendent researches, from experimenters both numerous and 
varied in their pursuit and object, which have come in upon this 
field of inquiry during the last few years. It is not less remark- 
able, that the subject of agricultural chemistry, perhaps more than 
any other, has demanded and successfully incited a rigid investi- 
gation of methods of research ; and it has, both in this country, 
in Germany, and in Prance, led to improvement, and a much 
greater degree of accuracy, in some of the most difficult depart- 
ments of chemical analysis. Besides the establishment of 



xnetliocls for the deteimination of qnailtitieB of ammonia and 
nitric acid, formerly far too minute to be made the aubject of 
snccessfiil qnantitative estimation, the analysis of gases, the 
pecoliar inflnences of the snn's rays, meteorological phenomena 
generally^ vegetable physiology in its various departments, struc- 
tural and functional, not a little aided by the revelations of the 
microecope, are all now receiving their special study, and will 
find their special application in the elucidation of important 
agricnltxtral questions. And, although we cannot &il to see 
that all will, sooner or later, conspire to give security to the next 
important step in these inquiries, it must be freely admitted, 
that as yet the difference of opinion is so great, and there really 
are so many points undetermined, that we may rest satisfied to 
delay for the present the summary we had intended to give, in the 
hope that, when the opportunity next occurs, we may have a less 
questioned advance to record. 

In conclusion, the field results recorded in the foregoing page» 
We clearly shown that, from some cause or other, the endeavour,, 
bf given mechanical operations, to attain a deep and porous 
stople, with the admixture with the surface of a certain portion of 
the subsoil, was quite insufficient to secure in the Bothamsted 
soQ those conditions of texture and of other qualities incident to 
it, essential to the successful start, and healthy afber-development, 
especially of an early thinly-seeded wheat crop. The field ex- 
periments also afford conclusive evidence, that the defect, so far 
as it was chemical, was not connected with a deficiency of avail- 
able mineral, relatively to available nitrogenous food. The con- 
clading experiments showed, on the contrary, that an increased 
provision of nitrogen in the soil, by manure, gave a very much 
larger amount of increase on the now more thickly-seeded land 
than an increased supply of the mineral constituents of the crop 
could do. That such should be the result on the land at Roth- 
amsted, where the Lois Weedon plan had failed, was perfectly 
consistent with the limited degree of porosity for the exposure of 
surface to atmospheric influences, and for the permeation of the 
Toots, which had been attained by the means employed. It is also 
perfectly consistent with those views as to the sources of the 
i^ultant effects of fallow, and as to the characteristic action of 
different constituents of manure on ordinarily cultivated land,' 
upon which we have so ofken insisted. 

The results in the laboratory again have borne their consistent 
endence on every point. Thus, bearing in mind at the same time 
tihe comparative character as to porosity of the Lois Weedon and 
the Rothamsted soils, it is found that, taking a given amount of 
^h in its natural state, both of these niore porous soils at Lois 



38 Th&Lois Weedon Flam, ofOrawing Wheal. 

Weedon cohfrnn more nitrogen than those at Itothamsted. One 
of them again has, besides its greater exposed surface in the 
field, no donbt associated with a greater susceptibility to atmo- 
spheric influences generally, a greater power of absorption for 
ammonia vin relation to a given surface. The other of these Lois 
Weedon soils, although absorbing a less amount of ammonia in 
relation to a given weight having an equal surface exposed, un* 
doubtedly offers, under equal circumstances in the field, a much 
larger amount of surface for absorption than the soils at Rotham* 
sted. Indeed, we can have little donbt, that to the difiference 
between the respective soils in the degree of the conjoint influ- 
ences of mechanical division, and of power of absorption and 
liberation (in part depending on it) of a sufficiency of available 
nitrogen relatively to the available mineral constituents, must in 
great measure be attributed the difference in the results obtained 
at Lois Weedon and at Bothamsted. 

Further, in the results which have been recorded, whether in 
the field or in the laboratory, we find additional confirmation of 
the view : — 

" That the chemical effects of fallow, in increasiDg the growth of the ceretl 
gfrains, are not measurable by the amount of the additional mineral food ol 
plants liberated thereby ; these being, under ordinary cultivation, in excess of 
the assimilable nitrogen existing in, or condensed within, the soil in the sams 
period of time. The amount of the latter, therefore — (».e.) the availahU 
nitrogen — is the measure of the increased produce of grain which will be 
obtained." 

But the system adopted by the Eev. Mr. Smith, of growing 
wheat year after year on alternate strips of the same land, and as 
a general rule without any restoration, directly or indirectly, of 
the mineral constituents removed in the crops, certainly does not 
come within the definition of " ordinary cuUivation^^ as referred 
to in the paragraph just quoted. Whilst, therefore, a soil not 
only rich in the absolute amount of the mineral constituents of 
the crop, but one capable of sufficient mechanical division, and 
susceptible to the liberating action of atmospheric influences, is 
absolutely essential to the success of the plan, yet all experience, 
practical and experimental, tends to show, that a large amount of 
inherent mineral stores, and their easy liberation, or available 
form for the use of the plant, will only suffice for the production 
of full crops of wheat, provided there be at the same time a liberal 
supply of available nitrogen wiihin the soil itself. 



Spoit%9UH}ocU d Co. PrinUrt, New'Strest Square, London. 



t 






ON SOME POINTS 



IN THE 



COMPOSmON OF WHEAT-GRAIN, ITS PRODUCTS 

IN THE MILL, AND BREAD. 



BY 



t J. B. liAWES, F.R.S., F.C.S., and J. H. GILBERT, Ph.D., F.C.S. 

I 



( LONDON: 

PRINTED BY HARRISON AND SONS, ST. MARTIN'S LANE, W.C. 

1867. 



REPRINTED BY SPOTTISWOODE <fe CO., NEW-STREET SQUARE. 

1893. 



ON SOME POINTS 



IN THE 



COMPOSITION OF WHEAT-GRAIN, ITS PRO 
DUCTS IN THE MILL AND BREAD. 

By J. B. LAWES, F.R.S., F.C.S., and 
J. H. GILBERT, Ph. D., F.C.S. 



The composition of the grain yielding the most important article 
of human food in temperate climates, its yield of valuable products, 
and the varying composition either of the grain itself, or of these 
products, according to the conditions of growth, or the circum- 
stances of after preparation, are subjects worthy the attention 
equally of states and of men of science. Accordingly, we find that 
a chemical examination of wheat-grain and its products, has from 
time to time been undertaken by chemists of repute ; sometimes 
as a matter of private investigation, and at others of public inquiry; 
and almost as numerous as the names of the experimenters, are 
the special lines of research which they have selected. 

We are indebted to Beccaria for the first notice, more than 
a century ago, of the gluten in wheat. Among the earlier investi- 
gators of the subsequent period, are, Proust, Vauquelin, 
De Saussure and Vogel, who have examined the proximate 
principles, and some of the changes to which they are subject, in 
various descriptions of wheat, of flour, or of bread. M. Bous- 
singault has somewhat elaborately studied various branches of 
the subject more recently; and we are indebted to Dumas, 

B 



2 LAWES AND GlLliERT 

Payen, Johnston, and Dr. R. D. Thomson for original, as 
well as a considerable amount of collected information. The most 
recent, on some points the most detailed, and from advance in 
methods, perhaps on some also the most reliable, are the resalts 
of M. Peligot in 1849, on the proximate constitution of various 
kinds of wheat, and of M. Millon in 1849 and 1854, on some- 
what similar points. Lastly, in 1853 M. Poggiale, and in 18oo 
Dr. Maclagan, have given the results of their investigations on 
the characters and composition of bread. 

Besides these more general investigations, we have had in 
recent times many special inquiries connected with our subject. 
Thus, M. Boussingault has given us analyses of the ashes of 
wheat; and many other such analyses have been made in Ger- 
many, and elsewhere, since the first appearance, in 1840, of Baron 
Liebig's work on " Chemistry in its Applications to Agriculture 
and Physiology." In this country, Mr. Way has given ua the 
most extensive series of wheat-grain-ash analyses, his list inclodingf 
those of 26 specimens or descriptions. 

The plan of our own investigation, which unfortunately has 
been much less perfectly filled up than we at first intended, was 
entered upon more than a dozen years ago, and was devised with 
reference to the following points : — 

1st. The influence of varying characters of season, and of vari- 
ous manuring, upon the organic and mineral composition of wheat 
grain. 

2ndly. The characters of varieties, especially in relation to their 
adaptation, and the qualities they then develop, under the influence 
of broader distinctions as to locality, altitude, latitude, and vary- 
ing climatic circumstances generally. 

It is in the second branch of the inquiry that we have fallen the 
furthest short of our intentions. With a view to its prosecution, s 
jouraey through the chief com growing districts of Europe, com- 
mencing at the northernmost point at which wheat is grown sno- 
cessfuUy, was about to be undertaken in 1848 ; but the social dis- 
turbances on the continent at that period, necessarily prevented it 
The plan proposed was — to collect information, as to the geological 
and meteorological characters of the various localities, as to the mode 
of culture, and as to the general acreage yield, both in straw and 
grain ; and lastly, to procure characteristic specimens for chemica' 
examination at home. Failing entirely in the execution of this 
design, the Exhibition of 1851 was looked forward to as an oppor- 



ON THE COMPOSITION OF WHEAT-GRAIN, &C. 3 

tunity for procuring specimens not only of wheat, but of other 
vegetable products, and perhaps also important particulars of their 
growth, from various countries and climates. Such, however, was 
the division of authority, and such the alleged preference given to 
public institutions in such matters, that, whether the latter bene- 
fited or not, the collection which we, as private individuals, were 
enabled to make, was entirely inadequate to our object. From 
these difficulties it is, that our second main object of inquiry was 
necessarily to a great extent abandoned ; and chiefly for this rea- 
son, but partly owing to the pressure of other subjects, the first 
or more limited or local branch of the investigation has in recent 
years been but imperfectly followed up. And, as it is probable 
that it must for some time remain so, it has been thought desirable 
thus to put on record .the results already obtained ; hoping that 
they may serve the double purpose, of confirming or adding to 
previously existing knowledge, and of indicating to others the 
points most requiring further study. 

The following is a brief outline of the plan of investigation 
which has yielded the results which we have now to lay before the 
Society. 

From the season 1843-4, up to the present time, wheat has 
been growing in the same field continuously, both without 
manure, by ordinary, and by various chemical manures. As a 
general rule, the same description of manure has succeeded year 
after year on the same plot of land. The amount of produce, grain, 
straw, and chaff, and its characters as to weight per bushel, &c., 
have in every case, been carefully ascertained and recorded. 
Samples from each plot — both grain and straw — have also been 
collected every year. Of each of these samples two weighed por- 
tions are coarsely ground ; the dry matter determined at a tempera- 
tore of 212°; and the ash by burning on sheets of platinum, in 
cast iron muffles arranged for that purpose.* Other weighed por- 
tions of grain and straw are partially dried, so as to prevent their 
decomposition ; and in this state they are preserved for any exami- 
nation of their organic constituents. By this course of procedure, 
a vast mass of results has been obtained, illustrating the influence 
of season and manuring, upon the percentage of dry substance, 
*^nd of mineral constituents, in the produce. In selected cases, 
the nitrogen in the grain, and in the straw, has been determined. 

* The dry matter and ash, were not determined in such complete series in the 
wrlier years, as in the later. 

b2 



4 LAWES AND GILBERT 

A summary table of these dry matter, ash, and nitrogen results, will 
be given below. In from twenty to thirty cases complete analyses 
of the grain-ashes have been made, and the results of these will 
be given in full. 

Besides the experiments above described, in selected cases, 
chiefly from the produce of the earlier years of the field experi- 
ments, it was sought to ascertain the comparative yield of flour^ 
and also the characters of the flour, of grain grown by diflerent 
manures in the same season, or by the produce of different sea- 
sons. The colonists steel haindmill was first had recourse to for 
this purpose. But it was soon found, that it was extremely diffi- 
cult so to regulate the machine, as to secure uniform action upon 
the different grains ; and it was further found, that the grain, and 
especially the bran, was cut up rather thaij crushed, so as to leave 
too much of flour in the portion separated as bran, and too much of 
bran in that separated as flour; and hence the results were not 
sufficiently comparable with those of the ordinary mill. Arrange- 
ments were therefore made for prosecuting the inquiry at a flour 
mill in the neighbourhood, worked by water power. Weighed 
quantities of the selected samples (from 125 to 250 lbs. each), were 
passed through the stones, and the ** Tneal" thus obtained, through 
the dressing machine, under our own personal superintendence ; 
great care being taken to clear from the different parts of the 
apparatus the whole of one lot, before another was commenced 
upon. 

The yield in the dressing machine of each of the different 
products was ascertained, and its percentage in relation to the 
total grain or its " meal," has been calculated. Portions of each 
of these products have had their dry matter (at 212*^, and their 
mineral matter (by burning on platinum), determined. The per- 
centage of nitrogen in a few selected series — from the finest flour 
down to the coarsest bran — has also been estimated ; and in the 
same cases, the amounts of one or two of the more important 
constituents of the ash have also been determined. The results 
of these dry matter, ash, nitrogen, and constituent of ash, deter- 
minations, in the series of different products obtained in the mill, 
will be given in tables further on. 

The original design, was to complete the examination of the 
mill products, by determining in several series of them, the per- 
centage of each of their proximate organic principles; and also 
the amount and composition of mineral matters, associated with 



ON THE COMPOSITION OF WHEAT-GRAIN, &C. 5 

them respectively. It was hoped, by this latter inquiry, to obtain 
important collateral information, bearing upon the influence of 
varioQS constituents upon the healthy and special development of 
the plant. Although, however, specimens of the flour are pre- 
served for this purpose, as well as the ashes of each crude pro- 
duct, it is feared that this subject cannot be proceeded with, at 
least for a considerable time to come. 

Portions of the different products of the dressing machine 
(Including more or less of the finest flour, of the more granular, 
or of the more branny particles respectively), from grains of 
somewhat various history of growth, have been experimented 
upon to ascertain their comparative bread-making qualities ; and 
these results, together with a few examinations of baker's bread, 
and a discussion of the results of other experimenters, as to the 
yield of bread from a given amount of flour, and the percentage 
of water and of nitrogen in the former, will be given below. 

With this short outline of the plan of investigation which 
has been pursued, we proceed now to a discussion of the results 
which have beeft obtained. 

In Table I are given, in the first four columns, certain pro- 
minent characters of the produce of each of ten years of the suc- 
cessive growth of wheat as above described. The items are : — 
The total produce per acre (grain and straw), in lbs. ; 
The per cent, of grain in the total produce ; 
The per cent, of dressed grain in the total grain ; and, 
The weight per bushel of dressed grain in lbs. 
f The figure given for each year, generally represents the 

\ average of about 40 cases ; and the characters enumerated are 
; the best which can be given in a summary and numerical form, 
to indicate the more or less favourable condition of the respec- 
tive seasons for the healthy development of the crop, and the 
5 perfect maturation of the grain. 

In the second set of three columns are given, side by side 
with the general characters just described, the percentages in 
the grain of each year — 
, Of dry substance ; 

j Of ash in dry substance ; and, 

f Of nitrogen in diy substance ; 

I VJie two former items being in most cases the average of 80 to 
^0 cases in each year ; but the per cent, of nitrogen, is in each 
instance, the mean of a few selected cases only. 



6 LAWES AND GILBERT 

In the third set of three columns, are given similar particu- 
lars relating to the composition of the straw. The percentages 
of dry substan3e and of ash in the straw are, however, not tie 
averages of so many cases in each year, as are those for the gram ; 
and the determinations of nitrogen in the straw, hav^e also been 
made in fewer cases than in the grain. 

It will thus be seen, that the table affords a summary view 
of a really enoi-mous amount of experimental result, and we 
ought to be able by its means to discover, at least the broad 
and characteristic effects of varying seasons, upon the compo- 
sition of the crop.* This indeed is all we could hope to attain, 
in such a mere outline and general treatment of the subject as 
is appropriate to our present purpose. 



TABLE I. 
General Summary. 





Farticalars of the Produce. 


Oompositiov 
Graix. 


I of 


Composition of 
Straw. 




Total 
g^rain & 


Percent, 
grain in 

total 
produca 


Percent, 
dressed 


Weight 
per 


Percent. 


Percent: Percent 


Percent. 


Percent. 


Percent 


Harvests 


straw 
per acre 


grain in 
total 


bnshelol 
dressed 


dry 


ash in 


nitrogen 


dry 


ash in 


oitrogeB 




in lbs. 


grain. 


grain in 
lbs. 


(212°.) 


dry. 


in dry. 


(213«.) 


dry. 


indxy. 


1846 


6646 


331 


901 


66-7 


80-8 


1-91 


2-26 


••• 


706 


0-92 


1846 


4114 


431 


93-2 


631 


84-3 


1-90 


216 


•■• 


6 02 


0-67 


1847 


5221 


36-4 


93-6 


620 


• • « 


•  • 


2-30 


• • • 


6-56 


0-73 


1848 


4517 


36-7 


890 


58-6 


80-3 


202 


2-39 


• • • 


7-24 


0-78 


1849 


5321 


40-9 


96'5 


63-5 


831 


1-84 


1-94 


82-6 


617 


0-82 


1860 


5496 


33-6 


94-3 


60-9 


84 4 


1-99 


215 


84-4 


6-88 


87 


1851 


6279 


38-2 


921 


62-6 


84-2 


1-89 


1-98 


84-7 


5-88 


0-78 


1862 


4299 


31-6 


921 


56-7 


83-2 


200 


1 2-38 


82-6 


653 


0-79 


1853 


3932 


251 


85-9 


60-2 


80-8 


2-24 


, 2-36 


81-0 


6-27 


120 


1854 


6803 


36-8 


95'6 


61-4 


84-9 


1-93 


, 2-14 


83 7 


6-08 

1 


0-69 


Means 


5063 


35-4 


92-1 


69-6 


82-9 


1-98 


2-20 


832 


617 


0-82 



Leaving then out of view all minor points, and confining our- 
selves to our already defined object — namely, that of ascertaining 
the general direction of the influence of variation of season upon 
the composition of the wheat crop— we cannot fail to see, that 
wherever the three items indicating the quality of the produce 

* It should be stated, that up to 1 848 inclusive, the description of wheat was the 
Old Red Lammas ; from 1849 to 1852 inclusive, it was the Red Cluster, and since 
that time the Rostock . The variations, according to season, both in the charactersand 
composition of the produce, are, however, very marked within the period of growlJi 
^»ach separate description. 



ON THE COMPOSITION OF WHEAT-GRAIN, &C. 7 

markedly distinguish the crop as favourably developed, we have 
a general tendency to a high percentage of dry substance, and to 
a low percentage both of mineral matter, and of nitrogen, in that 
dry substance. This generalization is more especially applicable 
to the grain ; but with some exceptions, mostly explicable on a 
detailed consideration of the circumstances and degree of its deve- 
lopment, it applies to a great extent to the straw also. 

Let ns take in illustration the extreme cases in the Table. The 
seasons of 1846, 1849, and 1851, with in the cases of the two 
latter large produce also, give us the best proportion of grain in 
total' produce, more than the average proportion of dressed grain in 
total grain, and the highest weight per bushel — a very significant 
character. With this cumulative evidence as to the relatively 
favourable development and maturation of these crops, we find the 
gnun in two of the cases, to be among the highest in percentage 
of dry matter; and in the third (1849), though not so high as we 
should have expected, it is still above the average. The per- 
centages of mineral matter and of nitrogen in the diy substance of 
the grain, are at the same time, in these three cases, the lowest in 
the series. The seasons of 1850 and 1854 again, with large 
amounts of produce, yielded also very fairly developed grain ; and 
coincidently they afford a high percentage of dry substance, and 
lower percentages both of mineral matter, and of nitrogen, in that 
dry substance, than the cases of obviously inferior maturation. 
With some exceptions, it will be seen, that the straws also of these 
five better years, give a tendency to low percentages both of mineral 
matter and of nitrogen in their dry substance. 

Turning now to the converse aspect, the season of 1853, shows 
Itself in the general characters of the produce, to have been in 
every respect the least favourable to the crop ; and it should be 
added that in this instance (as well as in 1845 to which we shall 
next refer), the seed was not sown until the spring. In 1853 the 
produce of grain was small as well as very bad in quality ; and 
with these characters, we have in the grain nearly the lowest per- 
centage of dry matter, and the highest percentage of ash and of 
nitrogen in that dry matter. In the straw, too, the dry matter is 
low, the ash somewhat high, and the nitrogen much the highest 
^n the series. In 1845, another year of spring-sowing, and at the 
same time of very bad quality of produce, we have nevertheless a 
Iwge amount of growth ; a fact which tends to explain some of the 
differences in composition as compared with 1853. Thus, 1845 



8 LA WES AND GILBERT 

gives US low percentage of dry matter, but not very high, either 
ash or nitrogen, in the grain. The straw, however, gives highpci^ 
centages both of ash and of nitrogen ; it being in the latter point 
next in order to 1853. The seasons of 1818 and 1852 again show 
low characters of produce. The former has coincidently Uie 
lowest percentage of dry matter in the grain in the series ; and 
both have high percentage of ash and nitrogen in the dry sub- 
stance of the grain. In the straw, the ash is in 1848 the highest, 
and in 1852 above the average ; tiie nitrogen in dry matter of 
straw being however in neither instance high. 

In several of the cases here cited, there are deviations from our 
general assumption on one point or other. But an examination 
in greater detail, would in most or all of them clear up the appa- 
rent discrepancy. When indeed, we bear in mind how infinitely 
varied was the mutual adaptation of climatic circumstances to 
stage of growth of the plant, in almost every case, it would indeed 
be anomalous, did we not find a corresponding variation on some 
point or other, in the characters or composition of the crop. Still, 
we have the fact broadly marked, that within the range of our own 
locality and climate, high maturation of the wheat crop is, other 
things being equal, generally associated with a high percentage of 
dry substance, and a low percentage of both mineral and nitro- 
genous constituents. Were we, however, extending the period of 
our review, and going into detail as to varying climatic circum- 
stances, interesting exceptions could be pointed out. 

It may be observed in passing, that owing to the general rela- 
tionships of the amounts of grain to straw, and the generally coin- 
cident variations in the percentages of nitrogen in each, the 
tendency of all these variations is in a degree so to neutralize each 
other, as to give a comparatively limited range of difierence in the 
figures, representing for each year, the percentage of nitrogen in 
the dry substance of the total produce — grain and straw together. 

The tendency of maturation, to reduce the percentages of 
mineral matter, and frequently of nitrogen also, is not observable 
in corn crops alone. We have fully illustrated it in the case of the 
turnip ; and our unpublished evidence in regard to some other 
crops, goes in the same direction. The fact is indeed very important 
to bear in mind ; for it constitutes an important item in our study 
of the variations which are found to exist in the composition both 
of the organic substance, and of the ash, of one and the same crop, 
grown under difierent circumstances. We may particularly observe, 



ON THE COMPOSITION OF WHEAT-GRAIN, &C. 9 

that the obvions reduction in the percentage of nitrogen in wheat- 
grain, the more, within certain climatic limits, the seed is perfected, 
is in itself a fact of the highest interest ; and it is the more so, 
when we consider how exceedingly dependent for full growth, is 
this crop upon a liberal supply of available nitrogen within the 
soil. 

Bearing in mind, then, the general points of relationship which 
have been established between the characters of the crop as to 
development and maturation on the one hand, and the percentage 
amounts of certain constituents on the other, let us now see — what 
is the general influence of characteristic constituents of manure^ 
upon the characters and composition of our wheat crop, which is 
allowed to remain on the land until the plant has fulfilled its 
highest function — ^namely, that of producing a ripened seed ? 

In illustration of this point we have arranged in Table III, the 
same particulars as to general character of the crop, and as to the 
composition of the produce, from several individual plots during 
the ten years ; instead of the average of the series in each year, as 
in Table I. The cases selected for the comparison are : — 

1. A continuously unmanured plot; 

2. A plot having an excess of ammonia-salts alone every 
year; 

3. The average of several plots, each having the same amount of 
ammonia-salts as the plot just mentioned, but with it, a 
more or less perfect provision by manure, of the mineral con- 
siihients also. 

It would be impossible to give the detail supplying all the 
results collected in this Table III ; but perhaps it is only proper 
that we should do so, so far at least as the percentage of nitro- 
gen in the dry substance of the grain is concerned. 



10 



LAWES AND GILBERT 



TABLE II. 

Determinations of Nitrogen per Cent, in the Dry Matter of 
Wheat Grain grown at Rothamsted. 



Harvests. 



EXPSBIMBNTfl. 



Unmanured. 



Manured with Ammonia- Salts only. 



Mean. 



1845 


2-28 


2-21 


2-33 


2-30 




2-28 


1846 


211 


212 


... 


... 




2 11 


1847 


211 


208 


222 


222 




2 16 


1848 


2-33 


2-34 


2-32 


2-37 




2-34 


1849 


1-85 


1-83 


1-91 


• • • 




1-86 


1860 


207 


 • • 


210 


2-07 




2-08 


1851 


1-80 


1-74 


1-89 


1-76 




1-80 


1852 


2-31 


223 


2-38 


2-31 




2-31 


1853 


2-26 


« • • 


2-33 


2-38 




2-32 


1854 


206 


206 


1-98 


1-96 




2K)1 



1846 


2-18 


2-29 


2-22 


2-23 


• • • 


2-23 


1846 


218 


212 


2-29 


219 


219 


1847 


2-35 


2-29 


2-42 


2-32 1 ... 


2-34 


1848 


2-39 


2-41 


2-39 


2-49 ' ... 


242 


1849 


1-89 


• • t 


204 


1-92 1 ... 


1-95 


1850 


213 


 •  


2 08 


219. ; ... 


213 


1861 


216 


212 


209 


2-25 1 ... 


215 


1852 


2-41 


2-50 


2-44 


2-68 


2-48 


1853 


2-43 


2-48 


2-37 


2-44 1 ... 


2-43 


1864 


2-31 


2-22 


2-31 


2-37 


 •  


2-30 



Manured with Ammonia- Salts and Mineral Manure. (Mixed Plots.) 



1845 


• • • 


•  • 


• a • 


• • • 


•  * 


• • • 


1846 


2-20 


214 


•   


214 


• • • 


216 


1847 


2-34 


2-38 


240 


2-42 


2-44 


240 


1848 


2.36 


• • • 


2-40 


2-42 


2-43 


2-41 


1849 


1-96 


1-97 


210 


207 


• •  


202 


1850 


216 


2-28 


225 


2-26 


•   


2-23 


1851 


200 


1-98 


202 


1-92 


  • 


1-98 


1852 


2-43 


2-34 


2-31 


2-40 


2-32 


2-36 


1853 


230 


2 34 


2-29 


2-28 


« • • 


2-30 


1864 


216 


1 ••• 

1 


212 


207 


• • • 


212 



ON THE COMPOSITION OF WHEAT-GRAIN, &C. 11 

It is necessary to make a few remarks in reference to this Table 
of more than one hundred nitrogen determinations. They were 
made by the method of burning with soda-lime, and collecting and 
weighing as platinum salt in the ordinary way. Few, perhaps, who 
have only made a limited number of such determinations, then 
only on pure and uniform substances, and who have not attempted 
to control their work at another period, with fresh re-agents, or by 
the work of another operator, will imagine the range of variation 
which is to be expected when all these adverse elements are to 
have their influence. It is freely granted, that the variations 
shown in the Table between one determination and another, on one 
and the same substance, are sometimes more than could be desired. 
The following, however, are the circumstances under which they 
have been obtained. Experiments 1 and 2 were pretty uniformly 
made by the same operator, but not all consecutively, or with the 
same batch of re-agents. It was thought, therefore, that inde- 
pendently of any variations between the two determinations, it 
would be desirable to have results so important in their bearings, 
verified by others. Accordingly, samples of each of the ground 
grains were given under arbitrary numbers, to two other operators, 
and their results are recorded respectively in columns 3 and 4; 
and where a fifth determination is given, it is a repetition by one 
or other of the experimenters last referred to. We should observe, 
that we have found it almost impossible to procure a soda-lime 
that will not give more or less indication of nitrogen when burnt 
with an organic substance not containing it ; and hence we have 
at length adopted the plan of mixing 1-2 per cent, of non-nitro- 
genous substance intimately with the bulk of soda-lime, igniting 
it in a muffle, moistening, and reheating it gently. After this 
treatment the soda-lime is free from ammonia-yielding matter. 
It should further be remembered, that a ground wheat-grain is 
by no means an uniform substance. Indeed, as we shall show 
further on, some of the particles of which such a powder is com- 
posed, may contain half as much again of nitrogen as others ; and 
thus any inefficiency in the grinding, or error in taking the por- 
tion for analysis, may materially affect the result. Notwithstand- 
ii^g all these circumstances, and the admittedly undesirable range 
of difference in the several determinations in some cases, it will 
^ observed, that generally three at least of the numbers agree 
suflBciently closely, and in some cases the fourth also. In fact 
after all, a study of the detailed Table must give considerable 
confidence, at least in the direction of the variations between the 
wwan results given in Table III, and in their sufficiency for the 
arguments founded upon them. With these remarks on the data, 
let US proceed with the discussion of Table III itself, which next 
foUowB : 



LIVI'ES AND GILBERT 



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i i S 1 1 1 1 i I 5 1 



ON THE COMPOSITION OF WHEAT-GRAIN, &C. 13 

A glance at this Table III, shows that the quantity of produce 
varies very mach indeed in one and the same season, according to 
the manuring. With these great diflferences in the quantities^ 
dependent on manuring, we have far less marked diflferences in the 
quality of this ripened crop, dependent on the same causes ; and 
this, with some few exceptions, is the same whether we look to the 
colamns indicating the general characters only, or the composition 
of the produce. That is to say, the same general distinctions 
between the produce of one season and another, are observable 
under the several varying conditions of manuring in each, as have 
been exhibited in the Table I of averages alone. In fact, season, 
or climatic variations, are seen to have much more influence than 
manuring, upon the character and composition of the crop. 

We have said that, other things being equal, the percentage 
of nitrogen in our wheat-grain was the lower the more the seed 
was perfected ; and we have also said, that nitrogenous manures 
greatly aid the development of the crop. But, an inspection of 
the columns of Table III which give the percentages of nitrogen 
in the dry substance of the grains produced under the three 
different conditions of manuring specified, shows us that there is 
almost invariably, a higher percentage of nitrogen where ammo- 
nia-salts alone have been employed, than where the crop was 
unmanured. We also see that, almost invariably, there is a higher 
percentage of nitrogen where mineral manures as well as ammo- 
nia-salts have been used, than in the produce of the corre- 
sponding unmanured plots. A closer examination shows, however, 
though the indication is not uniform, that there is nevertheless, 
an obvious tendency to a lower percentage of nitrogen, where the 
mineral constituents also have been employed, than where the 
ammonia-salts have been used alone ; and with this, there is on 
the average, a somewhat higher weight per bushel, indicating 
higher degree of maturation. Then, again, what are the circum- 
stances of these experiments, under which an increased percentage 
of nitrogen in the fixed substance of the produce, is obtained by 
a supply of it in manure ? The unmanured plot with its low per- 
centage of nitrogen in produce, is shown by the field experiments, 
to be greatly exhausted of the annually available nitrogen, relatively 
to the annually available mineral constituents required by the 
wheat crop. The plot, with the ammonia-salts alone, is shown 
by the field results to be defective in the requisite and available 
minerals, relatively to the available nitrogen^ and hence the crop 



14 LAWES AND GILBERT 

is grown under a relative excess of the latter. Again, the plots 
with mineral mannrea and ammonia-salts together, received so 
far an excess of the latter, as to yield, with the minerals, a larger 
crop than the average of the locality under rotation, and larger 
also, than the average of seasons would ripen healthily. It is then, 
under these artificial and abnormal circumstances, of the somewhat 
unnaturally low percentage of nitrogen, from obvious defect of it in 
relation to the developing and maturing capabilities of the season 
on the one hand, and the obviously relative excess of it on the 
other, that we got an increased percentage of nitrogen in wheat- 
grain by the use of it in manure. Even under these extreme 
conditions, the range of variation by manuring is very small ; and 
there is nothing in the evidence that justifies the opinion, that, 
within the range of full crops and healthy maturation, the per- 
centage of nitrogen in wheat-grain, can be increased at pleasare by 
the use of it in manure. That very opposite extremes of condition 
of soil- supply, may directly influence the composition even of 
wheat-grain, is however, illustrated in the percentages of mineral 
matter, as well as those of nitrogen, given in the table. Thus, 
taking the mean results only, we have with the relative excess of 
mineral constituents on the unmanured plot, the highest per cent, 
in the produce ; with the greatest relative defect on the plot with 
ammoniarsalts only, the lowest per cent, in the grain ; and with 
the medium relation in the other plots, the medium per cent, in 
the produce. Excepting, however, abnormal conditions, as already 
remarked, variation in climatic circumstances, has much greater 
influence on the percentage-composition of wheat-grain, than 
variation in manuring. 

Let us now turn to the composition of the ash of wheat-grain. 
Independently of the defect of a sufficient number of published 
analyses of wheat-grain ash, a dozen years ago, when we took up 
the subject, it was then generally believed that the composition 
of the ash of vegetable produce, would vary considerably with 
the supplies of the different constituents in the soil ; it was 
thought indeed, that according to the abundance of their presence, 
one base might substitute another, as for instance soda^ potash^ 
and so on. About the same time that we undertook a series of 
wheat-ash analyses, the ashes of various succulent vegetables were 
also analysed. This latter investigation led us to conclude, that the 
fixity of the composition of the ash of such substances, depended 
very much upon the degree of maturation of the produce ; and in 



ox THE COMPOSITION OF WHEAT-GRAIN, &C. 15 

fact that some constituents — soda and chlorine for instance — 
occurred in much larger quantities in the more succulent and 
unripe, than in the more elaborated specimens. It seemed to be 
perfectly consistent with this experience, to find in the ash of a 
comparatively perfected vegetable product like wheat-grain, a con- 
siderable uniformity of composition — such indeed as the analyses 
now to be recorded will indicate. 

These analyses were made ten years ago, by Mr. Dugald 
Campbell, and the late Mr. Ashford. And as, since that time, 
the methods of ash-analysis have in some points been improved 
upon, it will be well to give an outline of the plan then adopted ; 
especially as it is by a consideration of the tendencies to error on 
some points, that we must interpret the bearings of the actual 
figures given. On this point we need only add, that Mr. Camp- 
bell fully concurs in the tenor of our remarks. 

Method of Analysis : — Three portions of ash were taken. 

No. 1. In this the sand, silica, and charcoal, phosphate of iron, 
phosphoric acid, lime, and magnesia, were determined. The ash 
was dissolved in dilute hydrochloric acid, evaporated to perfect 
dryness, moistened with hydrochloric acid, boiled with water, and 
the insoluble matter collected and weighed, as — sand, silica^ and 
charcoal. To the filtrate, acetate of ammonia was added, and 
after digestion, the precipitate separated, dried, ignited and weighed 
— as phosphate of iron. To the filtrate now obtained, a solution 
of a weighed portion of pure iron dissolved in nitro-hydrochloric 
acid was added, then acetate of ammonia, and the mixture 
digested until the whole of the iron was precipitated as phosphate 
of the peroxide with excess of peroxide, from which was calculated 
the phosphoric a^id. From the solution filtered from the phos- 
phate of iron and oxide of iron, the lime was separated as oxalate 
and ignited as carbonate ; and from this last filtrate, the mugnesiaj 
by phosphate of soda and ammonia. 

No. 2. A second portion of ash was put into a carbonic acid 
apparatus, the acid, if any, evolved by means of nitric acid, and 
determined by the loss. The solution being filtered, sulphuric 
acid was separated by nitrate of baryta ; and afterwards chlorine 
by nitrate of silver. 

No. 3. To a solution of a weighed portion of the ash in 
hydrochloric acid, caustic baryta was added in excess, and the 
precipitate separated by filtration ; the excess of baryta was then 



16 LAWES AND GILBERT 

removed by carbonate of ammonia, and the filtered solution 
evaporated to dryness, the residue heated to redness and weighed ; 
water added, any insoluble matter deducted, and the remainder 
taken as chlorides of potassium and sodium ; a solution of chloride 
of platinum was now added to separate the potash ; the soda, being 
calculated from the loss. 

It is now admitted, that the separation of phosphate of iron 
from the earthy phosphates by acetate of ammonia as above 
described, is unsatisfactory ; and it is probable the amounts giren 
in the tables as phosphate of iron are too high, and if so, part of 
the difiTerence should obviously go to the earthy bases. For a 
similar reason it is possible that the phosphoric acid determinations 
may be somewhat too high — also at the expense of the earthy 
bases. Then again, it is well known that in practice the process 
for potash and soda, is one of some delicacy ; and that the tendency 
of manipulative error is to give the soda somewhat too high. We 
conclude upon the whole, that our phosphoric acid determinations 
way be somewhat high ; our phosphate of iron pretty certainly 
so ; and probably the soda also ; the other bases being, on this 
supposition, given somewhat too low. 

The wheat-grain ash-analyses, 23 in number, and referring to 
the produce of three separate seasons, and of very various manur- 
ing, are given in the following Tables — numbered IV, V and VI 
respectively. 



ON THE COMPOSITION OF WHEAT-GRAIN, &C. 



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ON THE COMPOSITION OP WHEAT-ORAIN, &C. 



19 



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LAWES AND GILBERT 





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ON THE COMPOSITION OF WHEAT- GBAIN, &C. 



19 



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20 LAWES AND GILBERT 

It is at once seen, that this ash may be reckoned to contain 
neither salphuric acid, carbonic acid, nor chlorine. The latter at 
least occurred only occasionally, and then in sach small quantitiesy 
as to lead us to the supposition that its presence is accidental, or 
at any rate not essential, in the ash of a perfectly ripened gprain. 
From the frequent absence of soda again, and from tlie uncertainty 
in its determinations as above alluded to, we are led to look at it 
as an equally unessential ingredient in the grain-ash of perfectly 
ripened wheat. Excluding then the chlorine, the soda, the iron of 
the phosphate of iron, and that portion of the matter collected as 
insoluble, which may have been soluble silica — the whole of these, 
on the average, amounting to a very few per cent. — the ash of 
wheat-grain is seen to consist essentially of phosphates oniLy ; the 
bases being potash, magnesia, and lime. The potash amounts to 
nearly one-third of the whole ash ; the magnesia to rather more 
than one-third of the potash ; and the lime to about one-third of 

the magnesia. 

If w^ now compare with one another the analyses of the eight 
different! ashes in 1844, those of the seven in 1845, or of the six in 
1846, having regard to the manures by which the crops were 
grown, it is impossible to say that these have had any direct and 
well-defined influence upon the composition of the ash of the grain. 
Thus we find, looking at the Table for 1844, that several of the 
plots manured with superphosphate of lime, yield a grain-ash 
having no higher percentage of phosphoric acid than that of the 
unmanured plot. Again, where potash is added (plots 15, 16, and 
18), the percentage of it in the ash is not greater than the average 
of the cases where it was not employed. And again, in the only 
case where soda was employed (plot 16), there is none of it found 
in the ash; nor, lastly, is the percentage of magnesia obviously 
increased by the use of it in manure. A similar detailed consi- 
deration of the composition of the ashes of the seasons of 1845 
and 1846, would, as already intimated, lead to ^ similar conclusion. 
In fact, the variations in the composition of the ash of this supposed 
ripened product, according to the manure by which it is grown, 
seem to be scarcely beyond the limits of error in the manipulation 
of the analysis ; though, one case at least of the duplicate analysis 
of the same ash — namely, that of No. 9, 1844 — indicates the range 
of variation from this cause to have been but small ; in the other, 
(No. 17, 1845) it was somewhat greater. 

Although the accuracy of the analyses may not be such as to 



ON THE COMPOSITION OF WHEAT-GRAIN, &C. 



21 



Bbow tlie difference in compoBition, if any, dependent on manure^ 
yet it is fonnd to be quite adequate to indicate the marked diffe- 
rences in the degree of development and mMuration of the grains, 
dependent upon season. Before calling attention to the figures 
illustrating tins point, it should be remarked that the season of 
1845 was the worst but one, and that of 1846 nearly the best, for 
ripening the grain, during the thirteen years of our continuous 
growth of wheat. And we shall find, consistently with this, and 
with the conclusions arrived at in connection with Tables I and 
III, that the variation in the composition of the ash is, comparing 
one year with another, much the greatest in the produce of the 
bad ripening season 1845, and much the least in the good ripening 
season 1846; This point, and some others, are illustrated in the 
following Summary Table, No. VII. 



LAWES AND GILBERT 



1 

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11 


IS 


pPP::?i 


1 


111 


ll 


p 


PPP.-i 


i 


1 
1 

1 


i\ 


ll 




priiM^i 


i 


i| 


SB 


|S 


ppp-°^ 


s 


i\ 




si 


Prii.ri 


s 
s 


|l 


ll 


•:| ■: 


?2|Sg? ;:: • 


 


ll 


:: -i 


stmi - - 


'■ 


il 


H| •■ 


i^llsi-- 


' 




Hi 






Wis 
II ti 

if S.S. 


idiliilli 
1 





OK THE COMPOSITION OF WHEAT-GRAIN, &C, 23 

Looking at the first Division of this Table YII, it is seen that 
in the item o{ phosphorio add,^ the variation in the percentage 
among the several caaes in each year, is the greatest in 1845, and 
the least in 1846; in ih^phosphaie of trcm, it is the greatest in 
1845; in the potdsh, it is the greatest in 1845, much less and 
about equal, in 1844 and 1846 ; in the soda, it is much the 
greatest in 1845, and much the least in 1846 ; in the magnesia^ it 
is again far the greatest in 1845, and it is the least in 1846. In 
the case of the Umej we have an exception to this general indica- 
tion, dependent on the too low amounts of it given for Nos. 2 
and 3, 1846 ; but if these are really in error in the direction 
suggested at the foot of Table YI, the indication would be the 
same as for the other constituents. We have then in the circum- 
stances of the seasons, and in the comparative characters of the 
produce coincident with these variations, the evidence that for 
one and the same description of grain, in a perfectly matured 
condition, the composition of the ash will be, within certain 
narrow limits, constant. 

So far as the constituents of the ash of the entire grain of wheat 
is concerned, we have only further to call attention to the three 
other Divisions of this Summary Table No. VII. In these are 
shown, side by side : — 

In the second Division of the Table, the mean composition of 
the ashes for each of the three separate years ; 

In the third Division, the mean composition for the three years 
together : (a) of the grain-ash from the unmanured plot — (6) of 
that from the farm-yard manured plot — (o) of the grain-ashes 
from all the other manures during the three years, including 17 
cases; and 

In the fourth and last Division, the mean composition of all 

our own wheat grain-ashes analyzed, 23 in number, by the side of 

the mean of 26 analyses of the grain-ashes of wheat, of different 

descriptions or grown in different localities, published by Mr, Way. 

We will go into very little detail discussions of these mean 

results, as the points they illustrate have most of them already 

teen alluded to. We may first remark, as a point to which we 

shall recur further on, that the mean percentage of lime, is the 

least in the bad year 1845, and the greatest in the good year 1846. 

Again, it is greater in the average from the manured plots, than 

in that from the unmanured. We may perhaps here anticipate 

hy Baying, that this is at any rate consistent with what we shall 



2i . LAWES AND GILBERT 

lifkerwards have to record, namely, that the ash of the finer Aonr 
—of which there is a greater proportion in the grain of the 
seasons of best maturation — contains more lime than that of the 
coarser and more branny portions of the grain. 

Lastly, in reference to this Summary Table, we would call 
attention to the mean composition of wheat gfaiu-ash yielded by 
the 26 analyses given by Mr. Way, by the side of that of the 23 
specimens grown at Rothamsted. Mr. Way's analyses, equally 
with our own, show that wheat grain-ash essentially condsts of 
phosphates of potash, magnesia, and lime. He, however, if we 
exclude silica, gives higher percentages of base, and a lower one of 
acid, than our own anaylses indicate. Mr. Way's average amount 
of phosphoric acid is indeed nearly 5 per cent, less in the ash t^ ^ 
ours. His series, however, included many descriptions of wheat, 
and our own only one — ^the Old Bed Lammas. In several of his 
cases, too, we observe that the percentage of this acid very closely 
approximates to our own average. 

We have now given a summary view of some points of the 
composition of the entire wheat-grain, and of its ash, as affected 
by varying season, and various manuring. We next turn to an 
equally summary statement, of a large number of experiments 
made in reference to the yieldj and composiium^ of the varions 
products separated in the milling process. The grains operated 
upon with this view, were of the same description of wheat, but 
grown experimentally in different seasons, and under different 
conditions of manuring. 

There have been many observations recorded as to the percent- 
age of flour obtained in practice from 100 parts of grain, and in a 
subsequent Table some of these will be adduced. We are also 
indebted to M. Boussingault for the determination of the flour 
and of the bran, yielded by 24 different descriptions of wheat, all 
grown side by side in the Jardin des Plantes at Paris. His 
method was to powder the grains in a mortar, and separate the 
flour and bran by means of a silken sieve. Results of this kind 
can, perhaps, scarcely be compared with those of the ordinary 
mill. The differences exhibited between the different specimens 
were indeed very great ; but the comparisons afforded within the 
series itself are interesting and very curious. 

In our own experiments, the so-called Cohnisfs steel hani-nxU 
was first had recoui*se to ; as it was thought that by its use, rather 



ON THE COMPOSITION OP WHEAT-GRAIN, &C. 25 

fhan tliat of an ordinary flour-mill, mnch smaller quantities of 
grain might be submitted to experiment, and that uniformity of 
working would also be more within our control. It was soon 
found, however, that in all cases the grain was, in this steel-^mill, 
rather cut np than crushed and rubbed down, as between ordinary 
mill-stones. It was also found, that the action in this respect 
varied considerably according to the speed of the operator, and to 
the precise set of the mill, which required to be varied according 
to the character of the grain. From these causes a statement of 
the amouTd of tlie yields of the various products obtained from the 
steel hand*mill, would be of little value. Though further on we 
shall have to call attention to some interesting points connected 
with the comparative composition of the several products of the 
grains mechanically separated in this way. 

We next determined to submit a series of the experimentally 
grown grains to careful, and as far as possible, uniform treatment 
between the stones, and in the dressing apparatus, of an ordinary 
flour-mill. The mill in question was worked by water-power. 
From 125 to 250 lbs, of the several grains were submitted to the 
experiment ; the whole of the apparatus being carefully cleared of 
the products of one specimen before another was commenced 
upon. The weights and samples of the " meals " as furnished by 
the stones, and of the several products separated in the dressing- 
machine, were taken under our own personal superintendence. 
Even here, and although every possible precaution was taken, 
considerable irregularities in the action of the apparatus were 
manifest, depending partly on the varying characters of the grain. 
Indeed it was clear, that to obtain results as to comparative yield 
of flour, strictly referable to the practical qualities of the respective 
grains, it would be necessary to operate on much larger quantities 
of each than those even now taken, in order that the miller might 
80 re-adjust the set of his stones, as the work proceeded, according 
to the character of the grain and of the meal which it afibrded, as 
to get from each its largest yield, as he would do in working upon 
considerable quantities. In all, twenty-eight lots of grain were 
operated upon in this way ; and although, as above implied, and 
ss will be pointed out further on, the results might in some points 
have been somewhat diflerent with larger quantities, yet the 
iniller, after a careful examination of all the products, decided \ 

that their general bearings were to be fully trusted. 

In some cases the meal obtained from the stones was separated 



26 LAWBS AND GILBERT 

in the dressing apparatas into nine products, and in others the 
products of the first three wires were taken together, constitatiDg 
the bulk of the^TM flour obtainable, and amounting to only aboot 
70 per cent, of the grain. In practice, however, the ibarth 
product of the dressing machine, " Tails" is generally redressed, 
and the fifth, ** Fine Shaa^ps " or " Middlings^' reground and 
redressed, together raising the amount of good bread-floor to 
about 80 per cent., or sometimes more. The sixth product is 
called "Coarse Sharps;** the seventh, " JUtw Pollard ;'* the eighth, 
** Ooa/rse Pollo/rd; " and the ninth, " Long Bran,'' It should be stated, 
however, that mills vary very much in the arrangement of their 
dressing machines in difieient localities, and even in the same 
locality ; so that the exact division of the prodacts here given, 
will not apply invariably. 

In Table VIII are given — 

1st. In the upper division of the Table, the percentage yield in 
100 meal, of each of the mill products, 7 or 9, as the case may be ; 
each figure being the mean of several experiments. 

2nd. (In the middle division of the Table) — The mean per cent, 
of dty substance (at 212°), in each flour, bran, Sac. And, 

3rd. The mean per cent, of mineral matter (ash), in each of the 
same mill products. 

As will be seen, seven of the specimens were grown in 1846, 
nineteen in 1847, and two in 1848; and in order to give some 
idea of the general character of the produce yielding the results in 
each of the separate columns, there is given at the head the mean 
bushels per acre, the mean weight per bushel, and the mean per 
cent, of grain in total produce, of the specimens to which the column 
refers. 



ON THE COMPOSITION OF WHGAT-aRAiN, &C. 



27 



TABLE Vm. 

Showing the yield of the different Mill PiFodaots from 100 of Grain ; and tbeir 

Percentages of Dry Substance and Mineral Matter. 



Prodocts Off Wires 1, S, and 3. 



losDi 



Ocnerel Characteniof Prodnoe :-• 

Mean bushes iier acre 

Mean weigrht per bastael (lbs.) 
Hean p.e.Krain in total produce 






n 



Mean 
of 3 

68-5 
43-6 



I 



0. . 



liean 
of 4 



S9; 
63'8 
4S-7 



1847. 



As 



Mean 
of 4 



S5; 

61 
86*9 



I 



^ 



Mean 

of 15 

caaee. 

33 

6S-S 

36-0 



1818. 




Mean 

of S 

cases. 

81* 
39-1 
37-1 



Means of all in eaoh 
year. 



1846, 
7 



S8 

63*4 

43-0 



1847, 
19 



8U 
6S'l 
36-0 



1848, 

S 



3U 
59-1 
37-1 



I 

So 

■a 



es'S 

37-8 



MS 

-51 



111 

'CS:a4 

as a> o 



Tield of Floor, Bran, ftc.. in 100 Meal. 



1* 5*** ^ 

J5}™» 

3. Tiire 8 ... ,,, 


44-0 

17-9 

8*7 


• •• 

• • • 


357 
10-4 
13-3 


• • « 
« • • 


47*4 

33-9 

SO 


44-0 

17-9 

8-7 


35-7 
16-4 
18*3 


47-4 

289 

S'O 


411 

18-6 

9*2 




Prodnoto 1, S, and 3, together. 

}-Tan» 

i. fine Sharps or Middlings ... 


70-6 

4*6 
8*7 


68-3 

51 
11-4 


66-4 

7-7 

10*3 


71-5 

5-3 
8-3 


73-8 

SI 
4*6 


69-3 

4-9 
10-3 


70*8 

6-8 
8-7 


73-3 

2*1 

4'6 


70^ 

6-3 
8*8 




7. Pine Pollard .*:; .".' 

8. Coarse Pollard 

t-UogBran 


3-1 
1-8 
6-6 
4-3 


3-8 
5*6 
S-7 
S-9 


3-6 
1-9 
7-4 
3S 


3'S 
1-8 
7-1 
S-8 


8-6 
S-6 
7*9 
59 


3*5 
3^ 
4-4 
3-6 


8-3 
1-8 
7-S 
S'5 


8-6 
fl-6 
7-9 
6-9 


8-4 

r4 

6-6 
3-0 





Per Cent. Dry Substance (at 212<* F.) in each Flour, Bran, &o. 



1. Wire I 

2. Wire S 

3. Wire 3 



• •• 



PfoducU 1, S, and 3,togeehtr. 

ITkOs 

t. Floe Sharps or Middlingi 



•• Ooarae Sharps ... 
7. Fine PoUard ... 
J. Coarae Pollard... 
•• Long Brsa 



• •• 

• «• 

• •« 

• •• 



... 


84*4 


• •• 


83-8 




85-4 


84*4 


83*8 


85'4 


84*8 


• •* 


84*6 


• •• 


83-7 




85'S 


84-6 


83-7 


853 


84-8 


•«. 


84-6 


• • • 


88-9 


• •« 


85*3 


84-6 


83-9 


85'3 


84-4 


IT. 


• •• 


84-7 


... 


83-8 


• •■ 


84*6 


83*8 


85*3 


84-1 




84*4 


sa-s 


84-8 


85*2 


86'6 


84-8 


85 -0 


85*5 


85-0 


• • • 


881 


84-9 


84-0 


84-7 


85-3 


84-1 


84-5 


85-8 


84*5 


• «• 


86*6 


851 


8S*S 


86'S 


85*4 


85'7 


85-3 


85-4 


83'4 




87'3 


85'8 


8SS 


85*6 


86-7 


86*4 


84-8 


85-7 


86-8 


**• 


86-4 


84-9 


82*6 


86-0 


86-3 


85-5 


85-3 


86*3 


85-4 


... 86'3 


85'6 


83-1 


85*6 


85-7 


85-8 


851 


85-7 


85-3 



Per Cent. Mineral Matter (Ash) in each Flour, 


Bran, 


&c. 






1. Wirel 
1 Wire 3 
)• Wires 


0-70 

0-71 

. 0-75 


• •• 

 •• 

• •• 


0<8 
0-71 
0-74 


• •• 


0*70 
0*73 
0-87 


0-70 
0-71 
076 


0-68 
0-71 
0-74 


070 
073 
0-87 


0*69 
071 
0*78 


•284 
•132 
•067 


Pndnets 1, fl, and 3, together. 

4. TUli 

*• Pine Sharps or Middlings '.'.'. 


••• 

0-93 
1-83 


0-71 

1-01 
1*88 


0-93 
1*54 


0-70 

1-08 
3*43 


• •• 

1-04 
1*88 


0-71 

0*97 
1-85 


0-70 

106 
3*24 


077 

1-04 
1*88 


0-71 

1-03 
213 


•483 

•054 
•186 


J-OnsTse Sharps 

J.FlMPoUard 

;.Corir«ePoUard 

••Long Bran 


3-77 
5-86 
6-91 
768 


4-35 
6*01 
6'85 
7-37 

*  • 


3-74 
5*45 
6*41 
6*67 


4*43 
5*65 
6*39 
7*19 


3*54 
5*03 
5*84 
6-34 


4-10 
5-94 
6-88 
7*43 


4-28 
5-61 
6'89 
7-08 

• •  


3-54 
6*03 
5-84 
6*34 

  • 


4-18 
5*65 
8*47 
711 


•142 
•136 
•420 
•213 


Total 


... 


 • • 


P634 



J 



28 LAWES AND GILBERT 

After the remarks already made, little need be said in detail 
regarding the comparative yield of the various products by 100 
parts of the different meals. It was decided by the miller, that 
pretty uniformly there was too much flour left in the fourth, but 
particularly in the fifth product ; and this, as an inspection of the 
Table will show, was obviated in the later experiments, namely, 
those on the grain of the harvest 1848. So far, then, the variation 
of the result is more due to the management of the miller, than to 
the intrinsic character of the grain. 

It is more interesting to observe, that a very careful examination 
of all the products led to the conclusion, that the grains grown by 
the more nitrogenous manuring, and consequently in the larger 
crops, provided they were well developed and matured^ allowed a bettor 
'separation of the flour, and less cutting up and intermixture of branny 
particles with it ; and hence, yielded a cleaner bran than the grain 
of the poorer crops. This was not the case, however, unless the 
highly -manured crops were at the same time well developed. It 
is consistent with this character of the grain of the more highly- 
manured crops, that the produce of the heavier and richer wheat- 
lands is generally admitted to yield a larger proportion of flour. 
The fact that the grain of richly-manured crops is frequently 
coarse, and not the good miUer^s sample, arises from the cireum- 
stance, not of the direct effect of rich manuring in depreciating 

the quality of the grain, but because the larger crops are more 
subject to injury due to climatic circumstances,; and are conse- 
quently frequently less favourably developed and matured. 

It will be observed, that the amount of long bran is always more 
than 2, and in the year of badly-ripened grain (1848), it is nearly 
6 per cent, of the total meal. This ninth product, together with 
the three or four immediately before it in the llisi, yield us nearly 
20 per cent, of the total meal, of such a braimy character as 
seldom to be used for human food. Some of the more recent expe- 
rimenters, MM. Millon and Peligot for example, have concluded 
that the amount of actual woody fibre in wheat^grain is seldom 
more than from 2 to 3 per cent. On this supposition, the nearly 20 
per cent, of the grain generally not applied directly as human food, 
would contain but a small proportion of necessarily indigestible 
woody matter ; and it would appear that there was very great 
room for improvement in the modes of preparation of the grain, if 

« 

* It would appear that, in a good ripening season, this condition is best attained 
when the crop is cut before the grain is perfectly ripe. 



ON THE COMPOSITION OF WHEAT-GRAIN, &C. 29 

\t were desirable to separate as ha man food in the first instance, a 
larger proportion of its nutritious matters. M. Poggiale, on the 
other hand, maintains that the quantity of woody-fibre refractory 
to the digestive organs, though not to chemical agents out of the 
body, is really very considerable.* But, of some points of the 
composition of the various products, we shall have to speak more 
in detail presently. 

In the second or middle division of Table "VTII, we have the 
average percentage of dry matter in the difierent products. In 
reference to these results it may be noticed, that, as might be 
expected, the percentage of dry matter is rather higher in the mill 
products, than it was in the entire gi-ains which yielded them. 
This is particularly the case in regard to the two specimens of the 
harvest 1848, the mill products of which give, on the average, a 
higher per cent, of dry matter than the samples of either of the 
other two years, although the dry matter of the entire grain of 
that season (1848), was very low. The difierences are therefore 
obviously more due to the circumstances of preservation and after- 
treatment, than to distinctions in the character of the respective 
grains. The only other remark which need be made regarding 
the varjring percentages of dry matter, is, that the branny, or more 
external portions of the grain, have pretty uniformly a higher 
percentage of dry matter than the more farinal internal portions. 

The widely difiering percentages of mineral matter in the several 
mill-products of the same grain, and the variations in this respect, 
even between the corresponding products in the difierent speci- 
mens, in the same, or in difierent seasons, are both more striking, 
and of greater interest. 

It is seen, that we have about ten times as high a percentage of 
ash in the ninth product, or bran, as in the first three, or purer 
floDTS. The percentage increases rapidly from the fourth to the 
mnth — ^that is to say, the greater the proportion of branny par- 
ticles. A careful examination of the moi-e detailed Tables also 
showed, that the variations in the percentage of mineral matter in 
the corresponding products of different specimens of grain, had 
a direct relation to the percentage, or relative position of the 
respective products, in the 100 of meal ; in other words, to the 

* Since the above was written, a very favourable report lias appeared in the ** Comptes 
Bendos ** (January 12, 1857), by M M. Dumas, Pelouze, Payen, Peligot, and Chevreul 
*~the Commission appointed by the Academy of Sciences, to inquire into the matter 
—OB anew process of M. M^go Monri^s, which claims to yield a perfectly white, 
wholesome, and agreeable bread, employing 86—88 per cent, of the entire grain. 



80 



LAWES AND GILBERT 



proportions of flour or of bran which they respectively contained. 
Although, however, the percentage of mineral matter is so very 
much greater in those portions of the grain which are not gency- 
rally used in the first instance as human food, yet, an inspection 
of the last column of the Table, showing the distribution of the 
mineral matter in the several products of 100 of meal, according 
to the amount of each of these, will show that, even in our first 
three products, we have nearly one-third of the whole mineral 
matter of the grain ; and adding to these a certain portion of that 
in the fourth and fifth products, which frequently contribute to 
the bread-flour, we shall have more than one-third of it in the 
currently edible portion of the grain. Further information as to 
the composition of the respective mill-products, and of their ashes, 
will be found in Tables IX, X, XI, and XII. 

In Table IX are given the individual nitrogen determinations 
in each of the several mill-products; those in the first three 
columns being by one experimenter, and those in the fourth 
column by another. In Table X is given a collective view of the 
composition of the same products, in regard to some other consti- 
tuents, as far as they have been determined ; including also the 
mean results of Table IX. 

TABLE IX. 

Determinations of Nitrogen per Cent, in Mill Products of 

Wheat-Grain. 

Harvest 1846; ground 1848. 





In natural state of dryness. 


Description of HUl Products. 


Experiments. 


Mean. 




1. 


2. 


3. 


4. 


I. TV ire I ... ••« ••• 
^. ff Jb ... •*• ••* 

9. ffV •■• ... *•• 


1-59 
1-64 
1-77 


]>69 
1-73 
1-78 


1-62 
1-69 
1-79 


... 

... 
... 


1-63 
1-69 

1-78 


4. IftllS ..■ .«• ••• 

6. Fine Sharps, or MiddUngs ... 


1*88 
2-20 


186 
2-20 


1-84 
2-22 


2-22 


1-86 
221 


6. Coarse Sharps 

7. Fine PoUard 

8. Coarse Pollard 

9. Long Bran... ■•• ..* 


2-58 
2-43 
2-41 
2-37 


2-52 
3-37 
2*32 
2-87» 


2-59 
2-48 
2-47 

... 


2-62 
2-48 
2 46 
2*42 


2-68 
2-44 
2-42 
2-39 



* By a third experimenter. 



i THE COMPOSITION OF WHEAT-ORAIN, 4c, 



n 





o 


















S 






s 




^■.a 




« 




t 


r 




* 






° 




1^ 


III 


g 


g 


ssSS 


• 




























5j 




























t 


SS3 


^ 


fe 


?52a 


K 




'-' 


*-• 








82 LAWES AND GILBERT 

The grain to which Tables IX and X refer, was an equal mixture 
of the produce from four different plots, very variously manured, 
and grown in the season 1 845-6 ; the harvest of which yielded one 
of the besb-matured grains throughout our series of field experi- 
ments. The wheat in question was, however, not ground until 
] 848 ; and we have in the percentage-yield of the respective pro- 
dacts, confirmation of the general opinion, that other things being 
equal, old wheat yields up its flour better than new. Thus, whilst 
in the average of the cases already recorded, we have little more 
than 70 per cent, of flour through the first three wires, we have 
from this old wheat 77f per cent. The products 4 and 5, from 
which a further yield of bread-flour is obtained, were correspond- 
ingly small ; but Nos. 8 and 9 were, on the other band, somewhat 
large. 

The particulars given in Table X are the percentages of Dry 
Matter, of Ash, and of Nitrogen, in the respective mill-products of 
this mixed grain. There are also given the percentages of MaJiUr 
insoluble in Add, and of phosphoric add in each of the nine ashes ; 
and in the last four columns we have the distribution of the total 
mineral matter, of the nitrogen, and also of the insoluble matter, 
and phosphoric acid of the ash, in each of the nine products, 
according to the proportion of the latter in 100 of the grain or 
meal. 

The percentage of Dry Matter in the several products from this 
old grain is, as would be expected, somewhat higher than the 
average from the grains of the same year which had not been so 
long stored. As before, the percentage of Dry Matter shows a 
tendency to increase as we proceed to the outer portions of the 
grain. The percentages of ash also show the same relations as 
already pointed out. 

Referring to the column of the percent